如图所示,重为25N的木块在大小为10N的水平拉力F的作用下,在10s内沿水平地面匀速前进5m,则物体受到的摩擦力为 N,拉力做的功为 J。
10 ;50
句型转换。
1. My day off was very boring.(就画线部分提问)
______ ______ your day off?
2. I did my homework yesterday.(改为否定句)
I ______ ______ my homework yesterday.
3. They had a very funny day, too.(改为否定句)
They______ ______ a very funny day, ______.
4. There were some seals at the aquarium. (改为一般疑问句,并作肯定回答)
______ there ______ seals at the aquarium?
Yes, ______ ______.
颗粒的沉降末速与颗粒的()、粒度和形状有关。
A、密度
B、浓度
C、温度
D、松散度