1- you travel by train or by air,you can reserve tickets onl

回答：应该是no matter whether,补充完整后,全句是No matter whether you travel by train or by air,you can reserve tickets online.
Whether和no matter whether都是“是否”之意,但whether是用来引导名词性从句,而no matter whether是用来引导让步状语从句.
如：Whether you travel by train or by air is up to you.(注：Whether引导了主语从句)
I wonder whether he will come or not.(注：Whether引导了宾语从句)
No matter whether you’ll come or not,we’ll make a final decision today.(注 No matter whether引导了让步状语从句)
欢迎提问,
不好意思,刚才未看到第二题.
回答：第二题应选A.这是个动词（短语）的时态题.选项B中用的是被动语态的一般现在时,这个时态表示经常发生的动作,而提问中的句子 “志愿活动可以培养自信(的证据)已经被证实（提出）了.” 句中谓语动词短语是的动作对现在,即说话时产生的影响,这时,需要用现在完成时,故选答案A.又如：
I have got in touch with him.我已与他联系上了.
欢迎追问,