3 make it possible for boats to travel 4 ports along the coast without being 5 to the dangers of the open.Some canals, such as the Suez and the Panama, save ships weeks of time by making their 6 a thousand miles shorter.Other canals permit boats to reach cities that are not 7 on the coast, still other canals 8 landsswheresthere is too much water, help to 9 fields wherethere is not enough water, and 10 water power for factories and mills.The size of a canal 11 on the kind of boats going through it.The canal must be wide enough to permit two of the largest boats using it to 12 each other easily.It must be deep enough to leave about two feet of water 13 the keel of the largest boat using the canal.When the planet Mars was first 14 through a telescope, people saw that the round disk of the planet was criss-crossed by a 15 of strange blue-green lines.These were called"canals"16 they looked the same as canals on earth 17 are viewed from an airplane.However, scientists are now 18 that the Martian phenomena are really not canals.The photographs 19 from space-ships have helped us to 20 the truth about the Martia"canals".

　　1.A.off B.with C.to D.by

　　2.A.way B.means C.method D.approach

　　3.A.waterways B.waterfronts C.channels D.paths

　　4.A.among B.between C.in D.to

　　5.A.revealed B.exposed C.opened D.shown

　　6.A.trip B.journey C.voyage D.route

　　7.A.lain B.stationed C.set D.located

　　8.A.escape B.drain C.dry D.leak

　　9.A.water B.wet C.soak D.irrigate

　　10.A.furnish B.afford C.offer D.give

　　11.A.focuses B.bases C.depends D.takes

　　12.A.cross B.pass C.move D.advance

　　13.A.down B.below C.beneath D.off

　　14.A.studied B.researched C.surveyed D.observed

　　15.A.few B.number C.deal D.supply

　　16.A.although B.because C.so D.if

　　17.A.that B.where C.when D.as

　　18.A.exact B.definite C.certain D.decisive

　　19.A.held B.taken C.got D.developed

　　20.A.find B.expose C.uncover D.discover

　　Cloze Test 20

　　1.【答案】C

　　【解析】parallel to"与……平行"，固定搭配。

　　2.【答案】B

　　【解析】means of transport"交通工具"，固定搭配。

　　3.【答案】A

　　【解析】waterways"水道";waterfronts指城市的滨水区;channels指海峡;paths指小路。

　　4.【答案】B

　　【解析】between指在两个港口间航行。among指三个或三个以上。

　　5.【答案】B

　　【解析】expose"使暴露、面临"后接to;reveal"显示";show"展示";open意为打开。本句意为暴露在危险面前。

　　6.【答案】C

　　【解析】voyage特指水上航行，其他选项均与水无关。

　　7.【答案】D

　　【解析】locate"位于";stationed"住扎于";set"放置于"。lie则不用被动式。

　　8.【答案】B

　　【解析】drain指排掉(过多的水);其他选项不符合题意。

　　9.【答案】D

　　【解析】irrigate指灌溉;soak浸泡，及其他选项不符合题意。

　　10.【答案】A

　　【解析】与介词for搭配的只有furnish。

　　11.【答案】C

　　【解析】depend on"取决于";base on"把……基于";take on"承担";focus on为集中注意力。

　　12.【答案】B

　　【解析】本句的意思是"运河必须有能够允许两条最大的船通过的宽度"。只有pass"通过"符合句意。Cross"穿过、横跨"与句意不符。