一 Amy, can we give away these soft toys? We               them for many years.

一 Mum, but l want to keep the bear.

人们在饲养金鱼时，常常往鱼缸里放一些新鲜的水草，其主要目的是（    ）

放在水平地面上重500N的木箱，受到水平向右100N推力时，恰好做匀速直线运动，则木箱受到的摩擦力是____ N．

To our surprise, all the l____ on the tree were eaten up by the cow soon.