采取导渗沟滤水还坡时,要先在()修做导渗沟。 ["堤脚处","堤脚外","堤坡上部","滑坡范围内"]
叉架类零件的视图应不少于()个。 ["1","2","3","4"]
“它非常凶猛,鱼鳍像一条条长带,鳍上的尖刺有很大毒性,它的胸鳍比身体还长,能将小鱼逼进角落,一口吞掉。”这段话描述的是()。 ["A、狮子鱼","B、海鲂","C、皇带鱼","D、石鱼"]
滤水还坡分为导渗沟滤水还坡、反滤层滤水还坡、透水体滤水还坡、()等。 ["土工膜还坡","土工织物滤水土袋还坡","塑料布还坡","黏土还坡"]
下列生物中,()在地球上存在了四亿年,和三叶虫一样古老。 ["A、鲨","B、鲎","C、蟹","D、虾"]
试述火炬冒黑烟和落火雨的原因?