Generally, the thicker a mammal's (哺乳动物) skin is, the less hair

His hard work ______ when he won the prize.A．paid offB．...

单项选择题His hard work ______ when he won the prize.

My father ______ an invitation to a dinner party, but h...

单项选择题My father ______ an invitation to a dinner party, but he ______ it.