I spent two hours on this maths problem.

I spent two hours on this maths problem. I spent two hours on this maths problem这句话里on this maths pro I spent two hours working out this problem.(改为同义句) I spent two hours on my homework.(改为同义句) I spent two hours on my homework.同义句 I spent two hours on my homework一句中spend为什么要用过去式spent Mary spent two hours ______ the math problem.[ 1分] he spent two hours -- this book.A.in read B.on reading C.in ( I spent two hours ______ my report. I spent almost two hours on the phone yesterday.I tried to f I spent（ ）（for;about）two hours on my homework last night I spent two hours making the cake.(同义句转换)