两个小组同意举行一次非正式会议。

The two groups agreed to hold an ___informal meeting.

他是那种理想的老师——直接、友好且不拘礼节。

He's the ideal sort of teacher - direct, friendly and ___informal.

“嗨”是一种非正式的打招呼方式。

"Hi" is an ___informal way of greeting people.