问题补充：
These plants are water .
A. each other day
B. every other day
C. each of two days
D. every of two days
答案：
A. each other day
(答案→)B. every other day
C. each of two days
D. every of two days
解析：每隔几天/周/月的表达是：every few days/ weeks/months。每隔一天是： every other day
