Having reached the highest point of our route according to plan, we discovered something the map had not told us. It was impossible to climb down into the Kingo valley. The river lay deep between mountain sides that were almost vertical（垂直）.We couldn’t find any animal tracks, which usually show the best way across country, and the slopes were covered so thickly with bushes that we could not see the nature of the ground. We had somehow to break through to the river which would give us our direction out of the mountains into the inhabited lowlands.
Our guide cut a narrow path through the bushes with his long knife and we followed in single file. Progress was slow. Then, when we thought we had really reached the river, we found ourselves instead on the edge of a cliff with a straight drop of 1,000 feet to the water below. We climbed back up the slope and began to look for another way down. We climbed slipped, sweated and scratched our hands to pieces and finally arrived at the river. Happily we came downhill along its bank without having to cut our way. However, after a few miles the river entered a steep-sided gap between rocks and suddenly dropped thirty-five feet over a waterfall. There was no path alongside it and no way round it.
Then one of the guides saw a way of overcoming the difficulty. There was a fallen tree lying upside down over the waterfall with its leafy top resting on the opposite bank below the falls. Without hesitation he climbed down the slippery trunk to show us how easy it was. Having got to the fork of the tree, he moved hand over hand along a branch for four or five feet with his legs hanging in space, then he dropped onto the flat bank the other side, throwing his arms in the air like a footballer who has scored goal, and cheerfully waving us on.
74．Having reached the highest point on their route, the travelers expected to be able to    .
A．track animals to the river
B．put away the maps they had been using
C．come near to the river from a different direction
D．get down to the river without much difficulty.
75．The travelers wanted to get to the river because      .
A．it would lead them to the waterfall
B．it would show them which way to go
C．it was the only possible way out of the mountains
D．it was a quicker way than going over the mountains
76．One reason why the travelers took so long to get to the river was that      .
A．it was too hot to move quickly
B．there was no proper path
C．they all tried to go different ways
D．they could not follow the animal tracks
77．To get past the waterfall the guide had to      .
A．use a fallen tree as a kind of bridge
B．cross the river above the waterfall
C．slide down a steep river bank
D．swing across the river from a high branch