单项选择题
The （） of the gravity disc is too big It causes oil to flow through the water outletWe changed the disc and no oil is found in the water outlet.
A.gravity B.diameter C.circumference D.cylinder
单项选择题 The designed （） is 20 tons per day, but the fresh water generator can only distil 15 tons at present.
单项选择题 The defective places in the furnace （） with fire bricks.
单项选择题 After fitting back in place the gear wheels, don’t forget to （） them.
