Nobody knows for sure what effect global warming has ___ our environment in the long term

（题文）Peter’s jacket looked just the same as Jack’s，but it cost________his.

New surveys suggest that people are more stressed and working longer hours than ever with technological tools constantly ______[ ]

_____you have to do the job, you should try your bestto do it well even though it may be very difficult for you.

Shortly after we ______, a waiter came overto us with a smile.