take turns to do sth 这个句型里“turn”为什么要加S啊?

take turns to do sth 这个句型里“turn”为什么要加S啊? take turns doing sth 这个句型里“turn”为什么要加S啊 take sb's turn to do sth 还是take sb's turn doing sth?为什么牛津字典里 take one's turns to do sth 和 It'one's turn to do sth 这两个句子对吗 in turn和take turns to do sth take turns to do sth造句 是take turn to do还是 take turns to do? tree turns green 为什么turn要加s Let's take turns to read our fact sheets.里的take turns 为什么不能用 We must take our turn at work这句话中的 our turn 要加 s turns 对take one's turn to do sth提问 take turn to do sth/take turn doing sth造句