It was a time ________ volunteers from all over the world visited this nursing home regularly.
| A．which | B．what | C．where | D．when |
Don't handle the vase as if it ______ made of steel.
| A．is | B．were | C．has been | D．had been |
Do you think this skirt is too tight ______ the shoulders?
| A．at | B．on | C．to | D．across |
Wethe difficulty together, but why didn't you tell me?
| A． | should face | B． | might face |
| C． | could have faced | D． | must have faced |
Birds' singing is sometimes a warning to other birds ______ away.
| A．to stay | B．staying | C．stayed | D．stayed |
______ at the door before you enter my room, please.
| A．Knock | B．Knocking | C．Knocked | D．To knock |