影响沙漠中植物生活的最主要非生物因素是 [ ]
A.阳光
B.空气
C.水
D.温度
答案:C
在如图所示的电路中,电源电压保持不变,闭合开关,当滑动变阻器的滑片P向右移动时电表变化情况是( )
A.示数变大,示数变小,与示数的比值不变
B.示数变小,示数变小,与示数的比值不变
C.示数变小,示数变大,与示数的比值变小
D.示数不变,示数变小,与示数的比值变大
Not until he arrived home _____ he find that this wallet had been stolen.[ ]
A. that
B. would
C. when
D. did