下图是俄罗斯部分地区人口分布示意图,该地区地势特点大致是( )
A:东高西低
B:西高东低
C:南高北低
D:北高南低
A: —I'm ____ (sad; excited) because we're going to climb the mountain.
B: —That's ____(grey; great).
A: —I'm ____(scared; tired).
B: —Why are you scared?
A: —Because she's going into the cave. I heard a____ (toys; noise).
B: —Be careful!
重20牛、体积为2×10﹣3米3的金属块浸没在水中,受到浮力的大小为____ 牛,方向____ ;若该金属块静止在容器底部,则金属块受到的合力为____ 牛.