勺子上还留有一粒微小的糖。

A minute ___grain of sugar remained on the spoon.

她又心不在焉地笑了笑，从钢琴盖上擦掉一粒灰尘。

She smiled again, absent-minded[ly], and wiped away a ___grain of dust from the lid of the piano.

毫无疑问，她是最佳候选人。

Without a ___grain of doubt, she was the best candidate.