提示问题:
1) How often do you exercise?
2) What's your favourite sport? Why?
3) When do you do sports?
下列能说明生物能对外界刺激作出反应的是( )
My sister ____ salty rice dumplings ____ sweet ones.
成年人在安静状态下的平均心率是( )
已知圆x2+y2+2x﹣2y+a=0截直线x+y+2=0所得弦的长度为4,则实数a的值是( )