I will endeavour to do my best for my country.
我将竭尽全力报效祖国。
I will contact you later to advise you when to come.
稍后我会与你联系，通知你何时前来。
I will send you a copy of the report.
我会把这个报告的复印本寄给你。
I will attempt to answer all your questions.
我将努力回答你的`全部问题。
I will contact you by letter.
我会给你写信联系的。