Of course, scientists can't answer all of your questions. If we ask, "Why is the ocean full of salt?" scientists will say that the salt comes from rocks. When a rock gets very hot or very cold, it cracks. Rain falls into the cracks. The rain then carries the salt into the earth and into the rivers. The rivers carry the salt into the ocean. But then we ask, "What happens to the salt in the ocean? The ocean doesn't get more slat every year." Scientists are not sure about the answer to this question.
We know a lot about our world. But there are still many answers that we do not have, and we are curious.
The main idea of this passage is______.
A.people feel cool when they are near a lake or river
B.scientists can explain everything we want to know
C.scientists can explain many things but not everything
D.the salt in the ocean comes from rocks
第2题
6岁男孩,患急性化脓性阑尾炎并阑尾穿孔,手术后5天仍发烧,腹痛,排稀便,考虑可能并发
A.急性肠炎
B.急性肠系膜淋巴结炎
C.美克尔憩室炎
D.腹腔残余感染
E.早期肠粘连
第3题
患儿男,5岁。急性化脓性阑尾炎并阑尾穿孔,术后第5天仍发热、腹痛、排稀便。最可能的手术并发症是
A.肠粘连
B.腹腔残余脓肿
C.梅克尔憩室炎
D.急性肠炎
E.急性肠系膜淋巴结炎
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