2, tit for tat [zh ē n f [zh ē n f ē ng xi ā ng du ē] for the needle. Metaphor is to counter an opponent's argument or action in an argument or struggle.
3. Pioneer [xiān fēng] (name) originally refers to the vanguard troops in March or wartime. Now it is a metaphor for an individual or a group that plays a senior role.
4. the warm front [nu m 4 n f ē ng] is located at the interface between cold and warm air masses and moves towards cold air masses.