Leave your key with a neighbor _______ you lock your-self out one day

The outbreak of this incident has given us much for thought, forcing us to ______ seriously on the past and the future.[ ]

Either you or he _______ to give them a lecturetomorrow.

__________ that it rains tomorrow, what shall we do? [ ]

Zhou Yang won the 1500-meter Olympic title at the Sochi Winter Games on February 15.—_______________________