be+被動不定式

根據(jù)語意的需要，“be+不定式”結構中不定式可以用被動式。如：

The cover is not to be removed. 這塊蓋布請勿揭開。

This medicine is to be taken hourly. 這藥每小時服一次。

The cost of carriage is to be paid by the receiver. 運費由收貨人支付。

She will determine how it is to be done. 她會決定這件事的做法。

A little tiredness after taking these drugs is to be expected. 服下這些藥后會有些疲倦。