密码是消费者使用银行卡的重要保障，请务必牢记，消费者在使用信用卡消费时必须使用凭密码消费方式，以确保帐户安全。
参考答案：错
The achievements of the greatest minds in science could never have been reached if it had not been for the patient and accurate work of hundreds of other people.
A．has it not been
B．if it had been
C．if hasn't been
D．had it not been
吊机的卷筒及滑轮在什么情况时需要更换？
