Why should you have a telephone in the bedroom(单选题) .Because we might use it to alert the burglar. .Because it’s convenient for us to talk to our friends while lying in bed. .Because it’s convenient for us to report to the police in case there is a burglary. .\xa0Because we might use it to make a phone call at midnight.
答案是:.Because it’s convenient for us to report to the police in case there is a burglary.
只能计算永续年金的现值，而不能计算它的终值。