问题
选择题
These plants are watered ＿＿ .
A．every a few days
B．every third day
C．every others day
D．each two days
答案
答案：B
短语：每几天every few days， few前不能加a，每两天every two days/ every other day，每三天every three days/ every third day，从四个选项中看出只有B表达正确。