Why the explosion occurred was ____the laboratory attendant had been careless.
| A．for | B．because | C．since | D．that |
Steve and Jane are both very good ___ chemistry.
| A．at | B．for | C．in | D．on |
Do you often help your father ___ the farm work during the summer vacation?
| A．for | B．on | C．in | D．with |
They sometimes go on working ___ the light of the moon.
| A．on | B．under | C．by | D．for |
He has never been to France, ___ Harry.
| A．neither has | B．nor did | C．so does | D．so has |
They don't study in NO 1 middle school, ___ those boys.
| A．so do | B．so don't | C．neither study | D．nor do |