Not only my father but also my grandpa_____ flying to Singapore this weekend.

问题描述:

Not only my father but also my grandpa_____ flying to Singapore this weekend.
a.is b.are c.was d.were

答案是A
not only..but also...做主语 谓语动词用就近原则,也就是说根据后面这个主语来决定谓语.
其次根据this weekend 可以判断出来是一般将来时,用现在进行时来表示一般将来.