▲在通常情况下，只用 which 即可。如：

Which has spots, the leopard or the tiger? 豹跟虎哪一个身上有斑点?

Which do you prefer, the town or the country? 城市生活和乡村生活，你更喜欢哪一种？

Which burns up more calories—swimming or cycling? 游泳和骑车，哪种运动消耗热量大？

Which would you sooner do—go swimming or play tennis? 你更愿意玩哪一样——游泳还是打网球？

Which do you believe has the strongest influence on how children develop—nature or nurture? 你认为先天条件还是后天教育对孩子的成长影响最大？

▲有时两种形式都可以，只是表达方式不同：

Which is the better exercise—swimming or tennis? 游泳和网球，哪种运动比较好？

Which kind of exercise is better—swimming or tennis? 游泳和网球，哪种运动比较好？

▲有时在 which 后面接名词或“kind of+名词”是为了使意思更明确。如：

Which (way) is quicker—by bus or by train? 怎么去更快——坐公共汽车还是坐火车?

Which (kind of) flavor do you want—chocolate or vanilla? 你要哪种味道的，巧克力味还是香草味？

Which (kind of material) do you want for your new dress, a stripe or a check? 你要哪种料子来做新连衣裙，条子的还是方格的?

但是下面这句，如果只用 which 会导致意思不明确：

Which kind of earrings did you buy in the end—the triangles or the circles? 最后你买了什么样的耳环——三角形的还是圆的？

Which earrings did you buy in the end—the triangles or the circles? 最后你买了什么样的耳环——三角形的还是圆的？

比较：Which did you buy in the end—the triangles or the circles?