Every year typhoons and losses lead to are frightening though measures have been taken.

问题补充：

Every year, typhoons and losses lead to are frightening though measures have been taken.

A. which

B. that

C. they

D. ones

答案：

A. which

B. that

(答案→)C. they

D. ones

解析：本题定语从句的先行词是losses，后面定语从句的主语是they，they指代名词typhoon在句中做主语，在losses后面省略了that，that指代先行词losses作为动词短语lead to的宾语，可以省略。句义：每年，台风以及台风带来的损失都是很可怕的，尽管很多措施已经被采取了。故C正确。