Mr. Brown is 70 this year. Although he is very old he works very hard. A. andB. butC. so

问题补充：

Mr. Brown is 70 this year. Although he is very old, he works very hard.

A. and

B. but

C. so

D. /

答案：

A. and

B. but

C. so

(答案→)D. /

解析：考查连词although用法。Although“虽然 --- 但是 ---”受汉语影响容易错选 but