测者纬度为30S,测得某天体的半圆方位等于050°SE,则其圆周方位等于()。
A.130°
B.230°
C.050°
D.310°
参考答案:A
If I ________ a million dollars, I would give it to medical research.
A.will have
B.have
C.had
D.am having
重20N的铁球从离地面40m高处由静止开始下落,若空气阻力是球重的0.2倍,那么该球从下落到着地的过程中,重力对小球做功为______J,空气阻力对小球做功为______J,小球克服空气阻力做功为______J,合外力做功为______J.