棒材坯料断面尺寸为（）。
A.902
B.1102
C.1202
D.1502
参考答案：D
Some students think that _____ English songs helps to improve their English a lot.
A．singing
B．sang
C．sing
D．sings
下列微粒中：①12Mg2+ ②③ ④O2-，核外电子总数相同的是 [ ]
A．①②④
B．②③④
C．①②③
D．①③④
③
④O2-，核外电子总数相同的是 [ ]