在职申硕英语习题练习

A．solved
B．discovered
C．broke
D．told
【单选题】： A     B     C     D  
Imagine fishermen walking down to the seashore, ready to carry out their early morning routine of preparing their boats and net. {{U}} (71) {{/U}} they hope for a good catch of fish.But to their {{U}} (72) {{/U}}, a horrible sight meets their still sleepy eyes. Thousands of fish have washed {{U}} (73) {{/U}}deaD、The cause of this mass destructionA、red tide!
Red tides are a global {{U}} (74) {{/U}}. They have been observed on both theAtlantic and the Pacific coasts of the United States andCanadA、They have also {{U}} (75) {{/U}} in many other places. Though relatively few people are {{U}} (76) {{/U}} them, red tides are not new.
In the Philippines, a red tide was first seen in the province ofBataan in 1908. Since then, red tides have been seen in many other {{U}} (77) {{/U}}.A、Philippines red tide expert told us that" {{U}} (78) {{/U}} the fish kills, the Philippines has documented 1,926 cases of dead shellfish poisoning caused by red tides".
The term "red tide" {{U}} (79) {{/U}} the discoloration of water that sometimes occurs in certain areas of the ocean or seA、Although the color is often red, it may also be {{U}} (80) {{/U}} of brown or yellow. The WorldBookEncyclopedia reports that "the discolored areas may range from {{U}} (81) {{/U}} a few square yards to more than 2,600 square kilometers".
What causes such discoloration Red tides are generally caused by several {{U}} (82) {{/U}} of single-celled organisms. These tiny organisms have hair-like projections which they use to {{U}} (83) {{/U}} themselves in water. There are about 2,000 varieties of these organisms, 30 of which carry poisonous {{U}} (84) {{/U}}. These minute organisms usually stay in warm waters with high content of salt.
A、red tide occurs when there is a sudden and rapid {{U}} (85) {{/U}} of these organisms. The concentration of these organisms may {{U}} (86) {{/U}} to 50,000,000 per quart of water!Although scientists do not fully understand why this happens. It is known that these organisms {{U}} (87) {{/U}} when certain conditions simultaneously affect the water. These include abnormal weather, {{U}} (88) {{/U}} temperatures, an oversupply of nutrients in the water, a generous {{U}} (89) {{/U}} sunlight, and favorable water currents. When a heavy rainfall occurs, minerals and other nutrients are sometimes washed {{U}} (90) {{/U}} the land into coastal waters. These nutrients can contribute to the breeding of the organisms. The result Red tides!

第5题：