このシステムのもとでは、生徒は交替で教えあい、お互いに助け合わなければなりません。

tbd

The basis of this system is that the students must take turns in teaching, they have to help each other.

王手をかけられたほうは、玉を逃げるなどの方法で王手を防がねばなりません。

tbd

The checked player must find a way for the king to escape and block the check.

何が正しくて何が間違いか選択するのは難しいが、選択しなければならない。

tbd

选择什么是“对”或“错”是一项艰难的任务，我们却必须要完成它。

It is a difficult task, choosing what is "right" or "wrong", but you have to do it.

It's difficult choosing between what's right and what's wrong, but you have to choose.

It's difficult choosing between what's right and what's wrong, but you have to make the choice.

私は眠らなければなりません！朝クラスがありますから。

tbd

I have to get to sleep! I've got classes tomorrow.

我必须去睡觉了！我明天早上有课。

鑑定をする時には、絵の真贋や保存状態等を調べる為、持ち主に本物を借りたりしなければいけなくなる。

tbd

When it is appraised, in order to check the authenticity and state of preservation of the painting, the real thing has to be borrowed from its owner.

外国人が日本に上陸する時は、到着した空港等で上陸許可の申請を行わなければなりません。

tbd

When foreign citizens land in Japan, they must apply for landing permission at the air or seaports where they arrive.

我々は時代に一歩先んじた見識を持たねばならない。

tbd

We must be a step ahead of the times in our outlook.

ローマのホテルの予約を、３日ずらさなければならなくなった。

tbd

I had to put back the hotel reservations for Rome by three days.

そして、入国審査官の審査を受けて上陸許可を受けなければなりません。

tbd

They must then go through a landing examination conducted by inspection officers before they can obtain landing permission.

しかし他のことも考慮に入れなければならなくなるだろう。

tbd

But other things would need to be taken into account as well.