The child tiptoed(翘起脚尖走) quietly to the bird. ______ into the forest when he was about to catch it.

sto develop their fullpotential, their education must be________ to their differences from others of the same age.

Was it because of the heavy snowstorm in Europe _______ the flight had to be put off ?

Not until the teacher explained theimportance of getting up early ______ we promise to come early.

Difficult as rumours on social media are _______，the government will step up supervision （监管）so that people will not be easily misled．