To compete more effectively with others, it is time that university students _____to study abroad after graduation. [ ]

It’s difficult for the village children to crossthe river to get to school.— I think a bridge ________ over the river.

His lost eyesightwas by his ever sharpening sense ofhearing.

Bicycling is a good exercise;________ it does not pollute the air.

When I left the island last night，_______ word came that _______strong wind would hit it soon.