黏度大的润滑油，适合用于载荷大、（）的场合。

     There are times when people are so tired that they fall asleep almost anywhere. We can see there
is a lot of sleeping on the bus or train on the__1__home from work in the evenings.A man will be
__2__the newspaper,and seconds later it__3__as if he is trying to__4__it.Or he will fall asleep on
the shoulder of the stranger__5__next to him.__6__place where unplanned short sleep__7__is in
the lecture hall where a student will start snoring(打鼾)so__8__that the professor has to ask another
student to__9__the sleeper awake. A more embarrassing(尴尬)situation occurs when a student starts
falling into sleep and the__10__of the head pushes the arm off the__11__,and the movement carries
the__12__of the body along.The student wakes up on the floor with no__13__of getting there.The
worst time to fall asleep is when__14__.Police reports are full of__15__that occur when people fall
into sleep and go__16__the road.If the drivers are__17__,they are not seriously hurt. One woman's
car,__18__,went into the river.She woke up in four feet of__19__and thought it was raining.When
 people are really__20__,nothing will stop them from falling asleep-no matter where they are.