Question

英语???????

Some people viewed the findings with caution, noting that a cause relationship between passive smoking and cancer remains ________.
A) to be shown
B) to have shown
C) to have been shown
D) being shown
为什么a?

Answer 1

这句子是被动的,先排除BD

然后to be done是指什么什么将被做

to have been done 有已经的意思

联系句意,所以就选A了

Answer 2

remain to do 是固定短语
句子意思应该是“消极的抽烟与癌症之间的关系有待被察看”
所以应该是被动