What we all know is that the old scientist, _______ life was hard in the past, still works very hard in his eighties.

15. Three quarters of the land here _____ wet land, an ideal place for migrating birds.

It’s difficult——– me to learn Englishwell.

I need some help ___________ my computer. It ___________.

n depend on it that I’m trying to do what is best, but _____ I have got to consider the cost.