__________ some medals came to live in the sea is not known.
| A．Which | B．Since | C．Although | D．How |
Li Fang is very busy，__________she’s always helping others with their lessons.
| A．but | B．although | C．so | D．for |
—Helen must obey her parents.
—Oh，she must，__________?
| A．must she | B．mustn’t she |
| C．shouldn’t she | D．should she |
We must do the experiment carefully__________Miss Liu told us.
| A．what | B．since | C．as | D．while |
__________ everybody is here，let’s set out right away.
| A．Now that | B．Because |
| C．For | D．After |
__________ the days went on，the situation there got worse.
| A．With | B．Since | C．While | D．As |