I won’t call you, ________ something unexpected happens.
Children’s brains can’t develop properly_______ they lack protein(蛋白质).
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 .