-_______ can the batteries (电池) keep these cool iPhones and iPads working?
- For about ten hours.
A. How much B. How many
C. How long D. How often
South Korean first female president, Par Geun-hye(朴槿惠) promised _______ her best to serve people.
A. do B. doing C. did D. to do
Detective Ken interviewed Jill and Jenny. They both denied ____ the vase.
A. steal B. stole C. stealing D. to steal
We _____ obey the new traffic rules to improve our road safety.
A. can B. must C. need D. may
It is seven o’clock. You will be late for school ______ you get up right now.
A. unless B. until C. when D. though
My grandparents are old, ______ they still work in the fields every day.
A. or B. so C. but D. and