—Of course, it's built over a canyon in the Zhangjiajie National Forest Park.
A:300-meter-deep
B:300-meters-deep
C:300 meter deep
D:300-meters deep
已知:|2x+y+3|+ (x−3y−5)2 =0,求3x﹣4y.
把下列各数的序号填在相应的横线上.①﹣0.3,②0,③5,④π2,⑤|﹣2|,⑥-83,⑦3.1010010001…(每两个1之间多一个0),⑧﹣227
分数:____ 整数:____ ,无理数:____
胎儿与母体进行物质交换的结构是( )