291.His bed-room is always ________.
A.at six and seven
B.at sixes and sevens
C.at sixth and seventh
D.at sixth and sevenths
292.He won a gold medal in the Olympic Games,but he was just ______ then.
A.at he age of 17 years old
B.a 17-years-old boy
C.a boy of 17
D.a 17-year boy
291.答案是B;at sixes and sevens=in a mess,意为:乱七八糟。
292.答案是C;at the age of通常作状语。此句也可以说:a 17-year-old boy。
