单项选择题
We have stayed at Shanghai port for a long timeThe fouling on the ship’s hull greatly increases her （）.
A.power B.speed C.resistance D.thrust force
单项选择题 We’d better （）economic speed （）fuel consumption.
单项选择题 This machine （）out of order very often, but now it works well.
单项选择题 When we arrived here yesterday, their ship （）for three days.
