You look troubled. –FD. happen to

There is someone knocking at the door.—It must be the computer repairman. I him to come to fix my computer.

Mr Black is an experienced engineer, and he will beemployed to ______ us in improving our equipment.

or little boy longed for a pretty toy train,______ his father could never afford.

He took down the old map on the wall and ______ a newone instead.