[填空题]
A and B rowers, who can r.b4qco 7at kb1 498zwv9o6avzf ppz m(ow at the same speed in still water, set off x5dfpw h1u fq;y93 x+tacross a river at the same time. A heads straight across a;tydwp1x 39uhf +fqx5 nd is pulled downstream somewhat by the current. The B heads upstream at an angle so as to arrive at a point opposite the starting point. Which rower reaches the opposite side first?
参考答案: A
本题详细解析: Both rowers need to cover the same "cross river" distance. The rtjdpi ,ees- /9,p, 8+gjuvuwhdos*e 7ower with the greatest speed in the "cross river" direction will be the one that reaches the other side first. The current has no bearing on the problem because the current doesn't help either of the boats move across the river. Thus the rower heading straight across will reach the other side first. All of his rowing effort has gont7 jd9,,je, u/oe s devpu8h-w*gpis+ e into crossing the river. For the upstream rower, some of his rowing effort goes into battling the current, and so his "cross river" speed will be only a fraction of his rowing speed.
