蓝藻细胞和菠菜的细胞的主要区别在于蓝藻细胞没有( )
A:细胞膜
B:细胞质
C:细胞壁
D:核膜
– What's the matter with Tommy? – He is ____________.– Oh, you can tell him to share worries with his friends and ____________.
学校合唱队员原来的女生人数占总人数的 25 ,后来又来了2名女生,这时女生人数占总人数的 37 .合唱队有男生多少人?