____ in reading the novel , he knewnothing about what was going on about him.

______ is very difficult.

Theory should by no means be separated from practice___, it’s important tocombine theory with practice.[ ]

填入下面一段文字横线处的语句，最恰当的一项是某一地区特定时间内游客数量超过其接待能力，是造成该地区旅游业出现种种问题的重要原因。若不提高其接待能力，再美丽的湖光山色也会暗淡无光， ，再动人的微笑服务也会丧失魅力。

Please be careful ______ your study ______ now on.