1.I'vedecidedtohavego,(leaving)myfearbehind.2.(Driven)byagreaterdemandforthiskindofsoftware,thecompanyhasemployedmoreengineerstoproduceit.3.(Reminded)nottomakeacallinclass,Borisalwaysturnsoffhiscellphoneduringthed

　　1.I'vedecidedtohavego,(leaving)myfearbehind.

　　2.(Driven)byagreaterdemandforthiskindofsoftware,thecompanyhasemployedmoreengineerstoproduceit.

　　3.(Reminded)nottomakeacallinclass,Borisalwaysturnsoffhiscellphoneduringtheday.

　　4.Youcan'tborrowbooksfromtheschoollibrary(before)yougetyourstudentcard.

　　我想知道括号里为什么填这些词,希望是详解,