题目

下列说法正确的是（ ）                                        A． H、H、H三种核素的性质不同       B．16O2、18O2彼此是同位素 C．14N、14C两种核素的中子数相同，质子数不同 D．白磷与红磷是磷元素的两种同素异形体 答案：D (   ) 8.——I really don't know            —I think the green one looks nice on you.A.   what should I chooseB.   what to chooseC.   which one should I chooseD.   which one to choose