导体对______的阻碍作用，叫做电阻，在国际单位中，电阻的单位是______，符号是______．

根据句意及首字母提示补全单词。

1. China has a p_____ of about 1.3 billion.

2. The bad air makes my chest hurt and it's difficult for me to b_____.

3. A_____ we have built the Green Great Wall, we still need to work hard to protect the environment.

4. W_____ you go there, please telephone me. I'll go with you.

5. There's no d_____ that computers are widely used by workers.