句型转换

1. We usually go to school by bike.(用by bus改为选择疑问句)

    _____ you usually go to school by bike _____ by bus?

2. My home is about 20 miles from here. (对画线部分提问)

    _____ _____ is your home from here?

3. I spent half an hour getting to school.(改为同义句)

    It _____ me half an hour _____ get to school.

4. We often walk home.(改为同义句)

    We often go home _____ _____.

5. I need to see my best friend.(改为否定句)

    I _____ _____ to see my best friend.

若测得某一级降解的药物在25℃时，k为0.02108/h，则其有效期为（）

A.50h

B.20h

C.5h

D.2h

E.0.5h