问题

Not for a moment ______ that this disease was caused by certain virus.

A:he have doubted
B:he doubts
C:did he doubt
D:he did doubt

正确答案是：

同类题型

Robert often asks us _______his Chinese, so his Chinese is much better than before.

He prepared for the text _______ many times _______ he could answer the questions quickly.

The house _____ Lu Xun used to live is now a museum.

I find __________ very difficult to learn English well.

How is he now? Is he slowly ____?