1. Finding planets is proving hard enough, but finding life on them will prove infinitely more difficult.
    寻找行星证明相当困难，但是要在行星上发现生命会变得无比艰难。

2. Frank smiled when he remembered his hard early years and the long road to success.
    弗兰克回想着他早年的艰难经历和走过的漫长的成功之路，微笑了。

3. Fifteen policemen had to push very hard to get him off the main street.
    15个警察不得不用很大的力气把它推离主要街道。

4. For countries that have lagged behind for so long, the temptation to move ahead in one jump is hard to resist.
    对于那些长期落后的国家来说，一跃而名列前茅的诱惑难以抵御。