【正确答案】 C

【答案解析】[解析] 听到新生儿的哭叫声，倦极了的母亲笑了。句中exhausted：疲劳的。sad：难过的，如：John is sad because his dog has died．约翰因为自己的狗死了非常伤心。gloomy：沮丧的，如：I can tell by your gloomy face that the news is bad．从你忧郁的脸上我能看出情况不妙。tired：疲倦的，如：I was too tired to walk any further．我累得再也走不动了。happy：快乐的，如：Their marriage has been a very happy one．他们的婚姻非常美满。只有tired意思上和exhausted最接近。