Pay attention to your studies. Read attentively lest _______

English is an international language. If you want to go abroad for higher studies,  you will have to learn English;

Time is so valuable   that it never comes back So, we must be careful of spending time.

Drugs are very dangerous for our health. It is high time we  avoided drugs

You look a little bit tired. Would you mind  making a cup of coffee

There goes the proverb that  time and tide wait for none So never waste your time for nothing.

It was long since  we had met last So, I did not expect that he would recognize me at first glance.