执行“从lxml导入etree"时出现错误通过pip成功安装lxml后，在python命令行中

    bash-3.2$ pip install lxml-2.3.5.tgz 
    Unpacking ./lxml-2.3.5.tgz
      Running setup.py egg_info for package from file:///Users/apple/workspace/pythonhome/misc/lxml-2.3.5.tgz
        Building lxml version 2.3.5.
        Building with Cython 0.17.
        Using build configuration of libxslt 1.1.27
        Building against libxml2/libxslt in the following directory: /usr/local/lib

        warning: no previously-included files found matching '*.py'
    Installing collected packages: lxml
      Running setup.py install for lxml
        Building lxml version 2.3.5.
        Building with Cython 0.17.
        Using build configuration of libxslt 1.1.27
        Building against libxml2/libxslt in the following directory: /usr/local/lib
        skipping 'src/lxml/lxml.etree.c' Cython extension (up-to-date)
        building 'lxml.etree' extension
        llvm-gcc-4.2 -fno-strict-aliasing -fno-common -dynamic -arch i386 -arch x86_64 -g -O2 -DNDEBUG -g -O3 -I/usr/local/include -I/usr/local/include/libxml2 -I/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -c src/lxml/lxml.etree.c -o build/temp.macosx-10.6-intel-2.7/src/lxml/lxml.etree.o -w -flat_namespace
        llvm-gcc-4.2 -bundle -undefined dynamic_lookup -arch i386 -arch x86_64 -g build/temp.macosx-10.6-intel-2.7/src/lxml/lxml.etree.o -L/usr/local/lib -lxslt -lexslt -lxml2 -lz -lm -o build/lib.macosx-10.6-intel-2.7/lxml/etree.so
        skipping 'src/lxml/lxml.objectify.c' Cython extension (up-to-date)
        building 'lxml.objectify' extension
        llvm-gcc-4.2 -fno-strict-aliasing -fno-common -dynamic -arch i386 -arch x86_64 -g -O2 -DNDEBUG -g -O3 -I/usr/local/include -I/usr/local/include/libxml2 -I/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -c src/lxml/lxml.objectify.c -o build/temp.macosx-10.6-intel-2.7/src/lxml/lxml.objectify.o -w -flat_namespace
        llvm-gcc-4.2 -bundle -undefined dynamic_lookup -arch i386 -arch x86_64 -g build/temp.macosx-10.6-intel-2.7/src/lxml/lxml.objectify.o -L/usr/local/lib -lxslt -lexslt -lxml2 -lz -lm -o build/lib.macosx-10.6-intel-2.7/lxml/objectify.so

    Successfully installed lxml
    Cleaning up...
    bash-3.2$ python
    Python 2.7.3 (v2.7.3:70274d53c1dd, Apr  9 2012, 20:52:43) 
    [GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
    Type "help", "copyright", "credits" or "license" for more information.
    >>> import lxml
    >>> import html
    Traceback (most recent call last):
      File "", line 1, in 
    ImportError: No module named html
    >>> from lxml import html
    Traceback (most recent call last):
      File "", line 1, in 
      File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/lxml/html/__init__.py", line 12, in 
        from lxml import etree
    ImportError: dlopen(/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/lxml/etree.so, 2): Symbol not found: _exsltDateXpathCtxtRegister
      Referenced from: /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/lxml/etree.so
      Expected in: flat namespace
     in /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/lxml/etree.so

对于旧版本的lxml2.3.4再次遇到相同的错误

get same error again for older version lxml2.3.4

    bash-3.2$ pip install lxml-2.3.4.tgz 
    Unpacking ./lxml-2.3.4.tgz
      Running setup.py egg_info for package from file:///Users/apple/workspace/pythonhome/misc/lxml-2.3.4.tgz
        Building lxml version 2.3.4.
        Building with Cython 0.17.
        Using build configuration of libxslt 1.1.27
        Building against libxml2/libxslt in the following directory: /usr/local/lib

        warning: no previously-included files found matching '*.py'
    Installing collected packages: lxml
      Running setup.py install for lxml
        Building lxml version 2.3.4.
        Building with Cython 0.17.
        Using build configuration of libxslt 1.1.27
        Building against libxml2/libxslt in the following directory: /usr/local/lib
        skipping 'src/lxml/lxml.etree.c' Cython extension (up-to-date)
        building 'lxml.etree' extension
        llvm-gcc-4.2 -fno-strict-aliasing -fno-common -dynamic -arch i386 -arch x86_64 -g -O2 -DNDEBUG -g -O3 -I/usr/local/include -I/usr/local/include/libxml2 -I/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -c src/lxml/lxml.etree.c -o build/temp.macosx-10.6-intel-2.7/src/lxml/lxml.etree.o -w -flat_namespace
        llvm-gcc-4.2 -bundle -undefined dynamic_lookup -arch i386 -arch x86_64 -g build/temp.macosx-10.6-intel-2.7/src/lxml/lxml.etree.o -L/usr/local/lib -lxslt -lexslt -lxml2 -lz -lm -o build/lib.macosx-10.6-intel-2.7/lxml/etree.so
        skipping 'src/lxml/lxml.objectify.c' Cython extension (up-to-date)
        building 'lxml.objectify' extension
        llvm-gcc-4.2 -fno-strict-aliasing -fno-common -dynamic -arch i386 -arch x86_64 -g -O2 -DNDEBUG -g -O3 -I/usr/local/include -I/usr/local/include/libxml2 -I/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -c src/lxml/lxml.objectify.c -o build/temp.macosx-10.6-intel-2.7/src/lxml/lxml.objectify.o -w -flat_namespace
        llvm-gcc-4.2 -bundle -undefined dynamic_lookup -arch i386 -arch x86_64 -g build/temp.macosx-10.6-intel-2.7/src/lxml/lxml.objectify.o -L/usr/local/lib -lxslt -lexslt -lxml2 -lz -lm -o build/lib.macosx-10.6-intel-2.7/lxml/objectify.so

    Successfully installed lxml
    Cleaning up...
    bash-3.2$ python
    Python 2.7.3 (v2.7.3:70274d53c1dd, Apr  9 2012, 20:52:43) 
    [GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
    Type "help", "copyright", "credits" or "license" for more information.
    >>> import os
    >>> import lxml
    >>> from lxml import etree
    Traceback (most recent call last):
      File "", line 1, in 
    ImportError: dlopen(/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/lxml/etree.so, 2): Symbol not found: _exsltDateXpathCtxtRegister
      Referenced from: /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/lxml/etree.so
      Expected in: flat namespace
     in /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/lxml/etree.so