When ______ comes to research into heart disease and its effects on the body, we do not have adequate substitutes for the use of animals.

We find ______ fast and comfortable to travel by plane.

What do you like to do _____ such a windy day?..[ ]

The boy is very fat ____ too much food.[ ]

We’ll have a hiking trip, but when shall we meet?— Let’s make it half past eightthe morning of June 1. [ ]