(2013·石家庄高三一模)Overuse of computers will ________ to the failure of our      eyesight, which is a warning to us all.

—May I speak to Mr.Smith?—I am afraid not.He is at a meeting now.It's not ________.

—Which of the three optional courses did you like best，Joe?—To tell you the truth，I didn't like ________ of them.

(2012·福建高考)China recently tightened its waters controls near the Huangyan Island to prevent Chinese fishing boats from ________ in the South China Sea.

 Many football fans attached great importance to the two matches, because China needed to beat Iran to ensure ______for the Asian Cup semi-finals.