— Oh dear! It is very cold today, ________?
— Yes, it is. You need to wear warmer clothes.
A:isn't it
B:it isn't
C:is it
D:does it
抗甲型H1N1流感的有效药物“达菲”可用莽草酸(化学式C7H10O5)制取.有关莽草酸的说法中正确是( )
青春是多彩的,又是矛盾的。下列属于青春期矛盾主要表现的是( )①独立性和依赖性的矛盾 ②自制性和冲动性的矛盾③开放性和封闭性的矛盾 ④主动性和被动性的矛盾