小明按一定的规律写数字：1、+2、-3、4、+5、-6、7、+8、-9…，当他写完100个数时，他停了下来．在他所写的数中，一共有______个正数．

125. The old man is quite able to take care of himself, he has seen the elephant. The underlined part means _____.

A．The old man knows the elephant.

B．The old man once saw the elephant.

C．The old man can take care of the elephant.

D．The old man is full of experience.