Did you ever have someone's name on the tip of your tongue and yet you were unable to reca

ll it？【C1】______this happens again, do not【C2】______to recall it. Do something【C3】______for a couple of minutes,【C4】______the name may come into your head. The name is there, since you have met【C5】______person and learned his name. It【C6】______has to be dug out. The initial effort to recall【C7】______the mind for operation, but it is the subconscious【C8】______that go to work to dig up a【C9】______memory. Forcing yourself to recall【C10】______never helps because it doesn't【C11】______your memory; it only tightens it. Students find the preparatory method helpful【C12】______examinations. They read over the questions【C13】______trying to answer any of them.【C14】______they answer first the ones【C15】______which they are most confident. Meanwhile, deeper mental activities in the subconscious mind are taking【C16】______;work is being done on the【C17】______difficult question. By the time the easier questions are answered, answers【C18】______the more difficult ones will usually begin to【C19】______into consciousness. It is often【C20】______a question of waiting for recall to come to the memory.

【C1】

A．As

B．When

C．While

D．Whether