题目

---- Hi, Vera, have you checked the account yet? ---- Certainly, I ______ it five times even though you told me to do it twice． A．checked                                          B．will have checked C．have been checking                          D．had checked 答案：A在Rt△ABC中，∠C=90°，AC=3，BC=4，则sinA的值是（ ）A．B．C．D．