We may find that learning a foreign language does not have to be________learning our mother tongue,but can in fact be twice ________.
Children’s brains can’t develop properly_______ they lack protein.
This is the very toy car ________ which he came here the other day.
I began to fish before memory began, _______ I know I have always fished.
_____ I had done it I knew I had made a mistake.
Elbert Einstein, for ______ life had once been very hard, was successful later in science .