We all know that __________ a foreign language requires time and effort (努力).

The world will be different and we will have to be more ready to_____ the changes.

_________ has Liu Xiang taken part inworld’s competitions of 110-metre hurdles— I’ve no idea. Let’s find it out on theInternet.

The outbreak of this incident has given us much for thought, forcing us to ______ seriously on the past and the future.[ ]

Everyone was in silence, having nothing to do but _________.