用手握住瓶子,使瓶子在竖直方向静止,如果握力加倍,则手对瓶子的摩擦力( )
A:握力越大,摩擦力越大
B:只要瓶子不动,摩擦力大小不变
C:方向由向下变成向上
D:手越粗糙,摩擦力越大
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??
下列各项中没有语病的一句是( )