单选题He earned enough money&nb

问题补充：

单选题Heearnedenoughmoneytostarthisownbusiness_____offeringguideservices_____tourists.A.by; toB.with; atC.on; forD.through; with

答案：

A解析介词by可以表示手段、原因，常置于动名词前，如：You can make the cake by mixing eggs and flour. 其次考查介词与动词offer的搭配，offer sth. to sb. = give sth. to sb.其中的to表示对象。