Do remember to be________. We must avoid any possible risks when doing this dangerous chemical experiment—burns, poisonous gases or cuts from broken tubes.

I don't think this question is worthy ____.

 As she is a _____ visitor to our house, we look on her as a part of our family.

If you sleep less than seven hours, you are three times more       to catch a cold．

Tired of the president’s _______ speech, the people _____ at the back began to play with their mobile phone.