Shall we say 8 February?请问这里say为什么含有"约定"的意思呢?这个例句是惯用的吗?

why shall we say thank you? Shall we say for a five? Shall we say 8 February?请问这里say为什么含有约定的意思呢?这个例句是惯用的吗? shall we shall we shall we shall we 帮翻译句话：no matter what you say we shall never lose heart 翻译shall we say soccer one night next week after school? Let's say good night to each other,shall we?怎么翻译 I'll mend this for you,shall we say for a fives?其中fives的意思? Actually I wanted to say on that day,Shall we never get apart,OK?汉语帮忙翻译下 When.shall.we.go. where shall we What shall we do? shall we do造句 shall we ( )now where shall we go?