A:30°
B:45°
C:60°
D:90°
小王大笑时由于用力过猛,使上下颌不能合拢,这是由于( )
读短文,填空
Hello ! My name is Amy .I'm a girl .I'm from England. Look !This is my father and this is my mother .My father is a teacher. My mother is a doctor .The boy is my brother .He's eight .He's a student .who's this girl ? Can you guess??