________ is often the case with children，Amy was better by the time the doctor arrived.
| A．It | B．That | C．What | D．As |
If you______the right map , we wouldn’t have got lost.
| A．have bought | B．bought | C．had bought | D．would buy |
—Which umbrella can I take?
—You can take______of them; I will use none.
| A．both | B．any | C．either | D．each |
Living in the desert involves a lot of problems，______water shortage is the worst.
| A．of which | B．when | C．of whose | D．Which |
Only when you have obtained enough data______ come to a sound conclusion.
| A．can you | B．you can | C．would you | D．you would |
Lessons______easily are soon forgotten．
| A．1earn | B．learned | C．to learn | D．learning |