I thought_ very useful to know the customs of foreign countr

I thought ______very useful to know the customs of foreign c i don't know whether the cars ___ to the far-reaching countr if you are traveling______ the customs are really foreign to 书上有个选择题（ ）I am,it is useful to know foreign languages答案是what _英语选择题要有理由______great help it is to know the customs of the he was very rude to the customs officer,()of course made thi what is the most important for a visitor to a foreign countr it's necessary to know different (customs) of sending gifts In order to figure out if the marriage customs of the Jews i __ I made some foreign friends,I found English very useful. To learn a foreign language we have to know the rules of ___ I think g is very useful,because I want to travel around the