The 【C4】______ of a canal depends on the kind of boats going through it. The canal must be wide enough to permit two of the 【C5】______ boats using it to 【C6】______ each other easily. It must be deep enough to leave about two feet of water 【C7】______ the keel of the largest boat using the canal. Some canals have sloping sides, while others have sides that are nearly 【C8】______ . Canals that are cut through rock can have nearly vertical sides. 【C9】______ , canals with earth banks may 【C10】______ if the angle of their sides is too steep. Some canals are lined with brick, stone, or concrete to keep the water 【C11】______ soaking into the mud. This also permits ships to go at 【C12】______ speeds, since they cannot make the banks fall in by 【C13】______ up the water. In small canals with mud banks, ships and barges (大平底船) must 【C14】______ their speed.
When the canal goes 【C15】______ different levels of water, the ships must be 【C16】______ or lowered from one level to the other. This is generally done by 【C17】______ of locks. If a ship wants to go up to higher water, the lower end of the lock opens to let the boat in. Then this gate closes, and the water is let into the lock chamber from the upper level. This raised the level of the water in the lock 【C18】______ it is the same as the upper level of water. Now the upper gates can be opened to 【C19】______ the ship into the higher water. Sometimes a canal contains a series of locks when the 【C20】______ in levels is very great.
【C1】
A.take
B.save
C.cost
D.waste
第1题
肾病综合征最基本的表现是
A、尿蛋白定量>3.5g/24h
B、尿颗粒管型
C、血浆白蛋白<35g/l
D、高度水肿(水肿)
E、高脂血症
第2题
肾病综合征最基本的表现是
A、尿蛋白定量>3.5g/24小时
B、尿颗粒管型
C、血浆白蛋白<35g/l
D、高度水肿
E、高脂血症
第3题
肾病综合征最基本的表现是
A.尿蛋白定量>3.5g/24h
B.尿颗粒管型
C.血浆白蛋白<35g/L
D.高度浮肿
E.高脂血症
第4题
肾病综合征最基本的表现是
A.尿蛋白定量>3.5g/24小时
B.尿颗粒管型
C.血浆白蛋白<35g/L
D.高度浮肿
E.高脂血症
第5题
肾病综合征最基本的表现是
A.尿蛋白定量>3.5g/24h
B.尿颗粒管型
C.血浆白蛋白<35g/L
D.高度浮肿
E.高脂血症
第6题
肾病综合征最基本的表现是
A.尿蛋白定量>3.5g/24小时
B.尿颗粒管型
C.血浆白蛋白<35g/L
D.高度浮肿
E.高脂血症
第7题
肾病综合征最基本的表现是
A.尿蛋白定量>3.5g/24h
B.尿颗粒管型
C.血浆白蛋白<35g/L
D.高度水肿
E.高脂血症
第8题
肾病综合征最基本的表现是
A.尿蛋白定量>3.5g/24h
B.尿颗粒管型
C.血浆白蛋白<35g/L
D.高度水肿
E.高脂血症
第9题
肾病综合征最基本的表现是
A.尿蛋白定量>3.5g/24h
B.尿颗粒管型
C.血浆白蛋白<35g/L
D.高度水肿
E.高脂血症
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