transition
n. 过渡; 转变; 变迁
搭配：transition from 由...过渡到...，由...转化成
in transition 转变中的
辨析：transport作交通之意时，实指运输工具；而traffic作交通之意时，指街上的行人车辆，着重数量得多少，所以，“交通拥挤”中的交通应该用traffic。
1.Adolescence is the period of transition between childhood and adulthood.
青春期是童年与成年之间的过渡时期。
2.The transition from IPv4 to IPv6, though, won't be painless.
尽管如此，从ipv4向ipv6过渡不会很顺利。
3.We adopt this measure to make the transition comparatively smooth.
我们有意识地采取这个办法，使得过渡比较顺利。
trial
n. 审判, 审理 ；测试, 试验, 考验；讨厌的人[事物], 忧虑[麻烦]的原因
搭配：be on trial在受审，在试验中
make trial of 试验，较量
put on trial 使经受考研
trial and error 反复试验，不断摸索
1.He's standing trial for thieving.
他正因涉嫌偷窃而接受审判。
2.When does zhouzhenglong's case come on for trial?
周正龙的案子什么时候开庭审理？
3.We shall put the machine to further trial.
我们将进一步试验这部机器。
4.The recorder next door is a great trial to us.
隔壁邻居的那台录音机响得真是让人受不了。
underlie
vt. 位于或存在于(某物)之下；构成…的基础(或起因); 引起
1.I think a lack of confidence underlies his manner.
我认为他表现出的态度是因为他缺乏信心。
2.Does some personal difficulty underlie his lack of interest in work?
是否有某种个人困难引致他对工作缺乏兴趣？
unexpected
adj. 没有料想到的, 意外的, 突如其来的
1.He is an unexpected guest to her.
对于她来说, 他可是位不速之客。
2.It was an unexpected disaster for the Chinese people.
对中国人民来说，这是一场飞来横祸。
3.Grandmother was quite taken with her unexpected birthday present.
祖母对这份意想不到的生日礼物喜欢得不得了。
4.I confess to being astonished at this unexpected statement.
我承认对这种未预料到的供词感到吃惊。
