—I wonder if I park my car here.
—Of course it does. You need to find a safer place.
A:when it minds
B:whether it matters
C:how it matters
D:if it works
如图为人体部分血液循环示意图,数字表示人体内的某些器官或结构,请分析回答:
What did the boy do last night?
在地球仪上,与地轴垂直并且环绕地球一周的圆是____.
体液中Ca2+含量太低时,神经、肌肉的兴奋性升高而出现抽搐。这一事实说明Ca2+的作用之一是