有的时候安装某个包时，需要更新其依赖的某些包，如下：

PS C:\Users\liguanlin\Desktop> conda install torchtext
Fetching package metadata .................
Solving package specifications: .

Package plan for installation in environment D:\Anaconda3:

The following NEW packages will be INSTALLED:

    tbb:         2019.4-h74a9793_0           defaults
    tbb4py:      2019.4-py36h74a9793_0       defaults
    torchtext:   0.4.0-pyhb384e40_1          https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/pytorch

The following packages will be UPDATED:

    cudatoolkit: 9.0-1                       defaults                                                    --> 10.1.243-h74a9793_0          defaults           
    pytorch:     1.1.0-py3.6_cuda90_cudnn7_1 https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/pytorch --> 1.3.1-py3.6_cuda101_cudnn7_0 https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/pytorch

Proceed ([y]/n)?

因为我的cuda是9.0的版本，所以更新后很大可能cuda不能使用了。先尝试如下命令：

PS C:\Users\liguanlin\Desktop> conda install torchtext --no-update-deps
Fetching package metadata .................
Solving package specifications: .

UnsatisfiableError: The following specifications were found to be in conflict:
  - cudatoolkit 9.0 1
  - torchtext
Use "conda info <package>" to see the dependencies for each package.

如果不行。可以使用如下命令：

PS C:\Users\liguanlin\Desktop> conda install torchtext --force
Fetching package metadata .................
Solving package specifications: .

Package plan for installation in environment D:\Anaconda3:

The following NEW packages will be INSTALLED:

    torchtext: 0.4.0-pyhb384e40_1 https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/pytorch

Proceed ([y]/n)? y

torchtext-0.4. 100% |###############################| Time: 0:00:00 791.51 kB/s
PS C:\Users\liguanlin\Desktop>

查看一个包的依赖情况：

PS C:\Users\liguanlin\Desktop> conda info torchtext
Fetching package metadata .................

torchtext 0.4.0 pyhb384e40_1
----------------------------
file name   : torchtext-0.4.0-pyhb384e40_1.tar.bz2
name        : torchtext
version     : 0.4.0
build string: pyhb384e40_1
build number: 1
channel     : https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/pytorch
size        : 40 KB
arch        : None
has_prefix  : False
license     : BSD
md5         : e8292705541ab1a49026bf4e3196af68
noarch      : python
platform    : None
requires    : ()
subdir      : noarch
timestamp   : 1565277734783
url         : https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/pytorch/noarch/torchtext-0.4.0-pyhb384e40_1.tar.bz2
dependencies:
    numpy >=1.11
    python
    pytorch >=1.2
    requests
    six
    tqdm