Today's Lesson Vol.071

At this time of year the 3rd year Taisei Junior High School students are very busy. This week they had the Taisei High School entrance exams (入試) and early next month they will sit entrance exams for public high schools. They are all studying very hard.

Many of the third year junior high school students have trouble with 'when' and 'if'.

Which word completes this sentence?

___________ the sun rises tomorrow, I will wake up.