If you _______ spit at all. please spit in the bucket provided. 

Sometimes smiles around the world ______ be false, hiding other feelings like anger, fear or worry.

(2014·山东省实验中学一模)You________get an all­expense­paid vacation to Australia if you can answer all the questions.

I set up email addresses for connecting with my parents last May. But I didn’t write to them as often as I ______. 

 You_______ play with fire, Tom. It's dangerous.