His wife, to whom he _____ for 20 years, died of cancer last Thursday. （ ）
A：had married
B：has been married
C：has married
D：had been married
在棱长为2的正方体内随机取一点，取到的点到正方体中心的距离大于1的概率____
被称为“遗传学之父”的科学家是（ ）
在激烈的篮球比赛中，人体骨骼肌细胞获取能量的方式是( )
小华想用空易拉罐来证明大气压强的存在，下列操作能达到目的的是（）
