请看下面一道题：_________ was very _________ that little Jim wrote the letter. A. It, careful              B. It, carefully           C. He, careful           D. He, carefully

【分析】此题正确答案为B was 的表语，从而误选了形容词 careful，并以此为依据在第一空误填了代词 He，误认为 He was very careful 是一个句子意群。其实，此题是一个强调句，其非强调形式为 Little Jim wrote the letter very carefully. 若用 it is … that… 的强调句式强调其中的状语 very carefully 即为上面一题的题干。请看下面几例，也属强调结构：
(1) It was when she was about to go to bed _________ the telephone rang.
A. since                 B. as                        C. that                        D. then 答案选C，被强调成分为 when she was about to go to bed 这一时间状语从句。，被强调成分为

(2) It may have been at Christmas _________ John gave Mary a handbag.
A. before                B. who                 C. that                 D. when
答案选C，被强调成分为 at Christmas，其中的动词 be 采用了 may have been 这一较为复杂的形式。

(3) Who was it _________ saved the drowning girl?
A. since                       B. as                  C. that                        D. he
答案选C，被强调成分为 who，该句实为 It was Tom that saved the drowning girl. 这一强调句的特殊疑问句形式(即对其中的Tom 提问而得)。

(4) What is it _________ his daughter needs most?A. what                       B. which                        C. that                        D. if
答案选C，被强调成分为 what，该句实为 It is a bike that his daughter needs most. 这一强调句的特殊疑问句形式(即对其中的bike 提问而得)。

(5) It was not until he came back _________ he knew the police were looking for him.
A. which              B. since                        C. that                        D. before
答案选C，为 He didn’t know the police were looking for him until he came back. 之强调句式。注：not…until…的强调句式通常为 It was not until…that… 的形式。