单项选择题
With the guide leading the way, the visitors were able to travel through the forest not by air but ______ foot.
单项选择题 Two dogs ______ a bone, and a third runs away with it.
单项选择题 — Who is that gentleman who talked to you just now — He is my uncle ______ marriage.
单项选择题 Tom! You're wanted ______ the phone.
