试题题干
On his travels, Houyi came —— the elixir of immortality, which he and his wife were supposed—— drink on the 15th day of the eighth lunar month when the moon is full and bright.
参考答案
正确答案：
试题解析
come on/ upon sb/sth意思是偶然遇见sb或sth
be supposed to do 应该做。。。