已知点Q（0，-7），它到x轴的距离是______．
点Q（0，-7）到x轴的距离是其纵坐标的绝对值，即为7．故填7．
A little knowledge is _______, because it can cause people to think they are more expert than they really are.
A．expensive
B．ordinary
C．precious
D．dangerous
半夏对胃肠道功能的影响是（）
A.抑制胃液分泌
B.降低游离酸
C.抑制肠蠕动
D.胃黏膜损伤保护
E.抑制胆汁分泌
