能引起人的眼睛视觉效应的最小能量为0.9×10^-18J，已知可见光的平均波长为0.6μm，普朗克恒量h=6.63×10^-34J•s，则一个可见光光子平均能量为______ J，能引起人的视觉反应时，进入人眼的光子数至少为______个．

In heavy seas the helmsman should steer the survival craft（）.

A.into the seas

B.broadside to the seas

C.in the same direction as the seas

D.in a series of figure-eights