When the flood of migrant birds was pouring thoug

请教“The warm weather sees the arrival of migrant birds ”中的“see”该如何理解?

请翻译下 这两个短语
1.The Ameraian population is highly migrant, and is likely to have a number of different jobs over a lifetime career, changing lacation accordingly, out of oure necessity.
"out of oure necessity" how to translate it?
2.No more than half an hour has passed since the teacher started the wxam, if that long.
"if that long" how to translate it?
thanx!
out of pure necessity
start the exam

这是什么语法?Rise of wages for migrant workers a must
Rise of wages for migrant workers a must
原文

英语翻译
The role of migrant workers
As is known to all,migrant workers have made a great contribution to the prosoerity of cities.They are an indispensable part of our workforce.Most of them wor+k on construction sites.There is no doubt that without migrant workers many of the construction projects would have to be held up for lack of manpower.

英语翻译
1.The Ameraian population is highly migrant,and is likely to have a number of different jobs over a lifetime career,changing lacation accordingly,out of oure necessity.
"out of oure necessity" how to translate it?
2.No more than half an hour has passed since the teacher started the wxam,if that long.
"if that long" how to translate it?
thanx!
out of pure necessity
start the exam