A:What do you think has happened to Tom
B:What do you think Tom has happened
C:Do you think what has happened to Tom
D:Do you think what Tom has happened
36+58=____
80-24=____
560+80=____
7200-2000=____
8600+700=____
直线3x+y-23=0截圆x2+y2=4所得的劣弧所对圆心角为( )
如图所示的是直升飞机在竖直上升时的情景,使直升飞机上升的力是( )
生物种类的多样性的实质是