The twins will go fishing with us this weekend _____ they are free.A though B if C whether D but

The twins will go fishing with us this weekend _____ they are free.A though B if C whether D but

B
条件状语从句,主将从现
如果双胞胎有空,他们就在这个周末跟我们去钓鱼

B

B 如果
句子的意思是这对双胞胎这个星期将会和我们去钓鱼，如果他们有空的话

b