There are 24 solar terms in a year. Grain Rain often starts in Apirl,the           month of the year.

Third

fourth

fifth

sixth

考查数词。句意：一年有24个节气。谷雨通常在一年中的四月开始。空格前有定冠词the,与可数名词单数month，要用序数词。根据

Grain Rain often starts in Apirl，可知四月份是一年之中的第四个月，要用序数词fourth。故选B项。

Only then_______ how much damage had been caused.

she realized

she had realized

had she realized

did she realize

“only＋状语”位于句首，整个句子用不完全倒装．此外，由then可确定用过去时态．

Daniel has undertaken to keep the secret, so he won’t tell anyone even though ______.

asked to keep

to be asked

to ask

asked to

考查省略和过去分词。句意：丹尼尔答应保守这个秘密，所以即使问他也不会告诉任何人。此处是even though引导的让步状语从句，从句主语和主句主语都是he，和ask之间是被动关系，相同的主语和be动词可以省略，所以这里是过去分词作状语，且ask sb. to do sth.可以省略与前面相同的部分，只留下动词不定式符号to。故选D。

Only when he returned ________ that the war had ended and the army had come back.

we tell

we told

did we tell

were we told

考查倒装句型。Only放在句首时，句子要用倒装语序；根据句意“我们被告知”可知，此处要用were we told。故答案选D。

He punished the children          their carelessness         making them pay for the damage.

by; for

with; by

for; by

about; with

考查介词。句意：他因为孩子们的粗心惩罚他们赔偿损失。根据句意可知：“their carelessness"表示他们被惩罚的原因，需用介词for表原因。"making them pay for the damage"表示他们被惩罚的方式，需用介词by表方式。故选C项。