1．(2019·浙江宁波十校联考)Whitecollar workers in China are willing to postpone their retirement age bluecollar workers prefer to retire early.
while 解析：句意：在中国，白领愿意推迟退休年龄而蓝领则更希望早退休。并列连词while在此表示对比。
2．(2019·哈尔滨三中模拟)For much of that time, she wanted to fly, never had the chance until now.
but 解析：她想飞，但一直没有得到机会，前后为转折关系，故填but。
3．(2019·吉林百校联盟联考)As a visitor or guest in a Chinese home or restaurant, you will find that table manners are essential in our daily life!
either 解析：根据空后的or可知，这里填either构成either...or... “……或者……”结构。句意：作为一个游客或者客人，在中国人的家里或者餐馆里，你会发现餐桌礼仪在我们的日常生活中很有必要。
4．(2019·重庆巴蜀中学一模)The visitors had just left the museum they heard a bomb explode at the exit.
when 解析：句意：这些游客刚离开博物馆就听到出口处传来炸弹爆炸的声音。这里用had just done sth. when...句式表示“刚做完某事就……”。
