1. There is a big dog_______to a fence outside the house.
A. tying B. tied C. to tie D. ties
【答案】B
【解析】
【详解】考查定语从句。句意：有一只狗栓在房子外的篱笆上。该句属于定语从句省略，补充完整为：There is a big dog（which is）tied to a fence outside the house。所以用过去分词作定语，故选B
2. ________ and see how long you can stay underwater.
A. Let off steam B. Take a deep breath
C. Pull your weight D. Rise to your feet
【答案】B
【解析】
【详解】考查动词短语词义辨析。句意：深呼吸，看看你能在水下呆多久。A.Let off steam发泄；B.Take a deep breath深呼吸；C.Pull your weight尽心尽力；D.Rise to your feet站起来。根据“ how long you can stay underwater”可知，深呼吸，看看你能在水下呆多久。故选B项。
