A:黄河下游成为“地上河”
B:夏秋季节我国东南沿海经常遭遇台风袭击
C:三江平原分布着大面积的沼泽
D:在丘陵低山上修梯田种植经济林木
Tony loves exciting things. He trekked the forests by himself last summer.
与小肠吸收营养物质无关的结构特点是( )
某次知识竞赛共有20道题,每一题答对得10分,答错或不答都扣5分,娜娜得分要超过90分,设她答对了n道题,则根据题意可列不等式____