单项选择题 The man stops to take his dog outside to do exercise because A．he doesn’t have enough time. B．he feels tired of running after his dog. C．he thinks his dog has mental problems. D．he treats the dog the way his parents treats him.

单项选择题 Lightning bugs can blink themselves because of a chemical substance A．in the head. B．in the tail. C．in the abdomen, D．in the wing.

单项选择题 According to the man, the computer had problems EXCEPT that A．it couldn’t connect to the Internet. B．it crashed repeatedly in some cases. C．its modem was broken. D．its screen didn’t function well.