13．When was the last time you saw three men running down a forest trail（小徑）in the rain wearing flipflops（拖鞋）？That's what my friend Brandon，Josh and I were doing last autumn．We were looking for a waterfall（瀑布）．We didn't have much time to get to the waterfall and back，so we were running．We were wearing flip-flops to prevent our shoes getting dirty． It was raining，but lightly．It kept us cool as we climbed over giant stones and through a shallow（淺的）stream．We followed red arrows（箭頭）and crossed that stream several times，walking on toward the promised waterfall．Time was not on our side，howevr，and we were forced to turn around．As we started back，we looked at the shallow stream we had just crossed．Where did this rushing river come from？That was when we realized a flash flood was around! In the few minutes the water rose at a fast speed．Now there were no big stones tobe seen-only what looked like lumps（隆起）covered with rushing water．We had no choice but to move our way back carefully in the rushing water-in flip-flops．We had crossed the stream not once or twice，but six times in search of a waterfall that we never even reached! With most of the crossings，we needed each other's help if we didn't want to be washed away by water．Wet all over，we felt relaxed after we made the last crossing． "My dad always told me to keep off a river when travelling in the rain．"Josh said as we hurried back down the path． "Why didn't you tell us that earlier？"I laughed． "Would it have made a difference？"came the reply． He had a point． 26．Why were there no big stones to be seen in the stream when they came back？C A．The big stones were moved away by someone else． B．They were runningtoo fast to notice the big stones． C．The big stones were covered with rushing water． D．The big stones were washed away by rushing water． 27．Why didn't they find the waterfall in the end？D A．Because they were short of time． B．Because they were wearing flip-flops． C．Because Josh kept warning thm not to go any further． D．Because the flood prevented them from going forward． 28．We can infer（推斷）from the passage that the writer and his friendsD． A．were crazy about outdoor activities B．made full preparations before the trip C．crossed rushing water easily in the end D．had much experience in travelling in the rain．
