We were doubtful about the practicability of the plan.

我们怀疑这个计划是否切实可行。

《牛津词典》

At first we were doubtful about employing Charlie.

一开始我们对是否录用Charlie心存疑虑。

youdao

At first we were doubtful about employing Charlie.

一开始我们对是否录用Charlie心存疑虑。

youdao