第一题 填 that 是 not until的强调句型
第二题 C
Not until 提前 表否定 句子需要部分倒装 所以借助助动词did
句首为否定或半否定的词语,如no,not,never,seldom,little,hardly,at no time,in no way,not until… 等.
Never have I seen such a performance.
Nowhere will you find the answer to this question.
Not until the child fell asleep did the mother leave the room.
当Not until引出主从复合句,主句倒装
典型例题：
1） Not until the early years of the 19th century___ what heat is
A.man did know B.man knew C.didn't man know D.did man know
答案为D.否定词Not在句首,要求用部分倒装的句子结构.
2） Not until I began to work ___ how much time I had wasted.
A.didn't I realize B.did I realize C.I didn't realize D.I realize
答案为B.