[单选题]Even our face often uses muscles. But if we want to save our energy, try smiling instead of frowning. Remember that it takes 17 muscles in our face to smile, but 43 muscles to frown!
根据上述段落补全句子：Smiling uses less energy than（）.
A
frowning
B
a lot of fibers
C
to digest food
D
to function properly
正确答案：A
题目解析
段落中的句子“But if we want to save our energy, try smiling instead of frowning .”关键词“save our energy”“smiling instead of frowning”知微笑更省力。
