(A) Danger can be
(B) They can be dangerous
(C) What can be dangerous
(D) While danger (93.1)
[答案] C what引导的主语从句。What既是从句的连词,又是从句的主语。
(3) —— has been a topic of continual geological research.
(A) Did the continents originate
(B) How did the continents originate
(C) Have the continents originated
(D) How the continents originated (91.1)
[答案] D How 引导的主语从句。
(4) —— progress helps to relieve scarcities is a fact accepted by economists.
(A) Technological
(B) That technological
(C)Although technological
(D)There is technological
[答案] B. That 引导的主语从句,当连续读到两个谓语动词(e.g. Helps…is),而空格在句首,应首先考虑主语从句。这是主语从句典型的句子结构。
,托福语法指导-从属连词及真题要点解析