已知氢有三种常见的同位素:1H、2H、3H氧也有三种同位素:16O、17O、18O,由这六种核素构成的水分子中,其式量最多有
A.18种
B.12种
C.7种
D.6种
答案:C
My name ____ Jack . Kangkang and Maria ____ my friends.
A. is; are B. is; is C. are; is
与花岗岩有关的矿床