A:电子数为78
B:质子数为53
C:中子数为78
D:质量数为131
①____ A.read B.play C.book ②____ A.Friday B.Wednesday C.birthday
③____ A.sports B.Monday C.Friday
④____ A.weekend B.science C.music
⑤____ A.maths B.often C.Chinese