_______it not been for the free ticket, I would not have gone to the cinema.
| A．Were | B．Should | C．If | D．Had |
__ many times, but she still didn't know how to do it.
| A．She was taught | B．Having taught | C．Having been taught | D．She has taught |
Scientists think that the continents ____ always where they ___today.
| A．aren't; are | B．aren't; were | C．weren't; are | D．weren't; were |
--- Would you tell me ___ you want your tea, with sugar or milk?
--- Sugar, please.
| A．whether | B．where | C．what | D．how |
Leaves are found on all kinds of trees, but they differ greatly __ size and shape.
| A．on | B．from | C．by | D．in |
He began to take political science_____ only when he left school.
| A．strictly | B．truly | C．carefully | D．seriously |