A.30°
B.45°
C.60°
D.90°
[单选题]A.30°B.45°C.60°D.90°
[单选题]A.B.C.D.
[单选题]A.xyB.2xyC.D.xy+1
[单选题]A.B.X是第二周期VA族元素C.X是第二周VIA族元素D.X的最高化合价为+4