‌因果信号<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/4277a60bdf52460281b963a9c7deba22.png?x-oss-process=image/sharpen,200"/>的拉普拉斯变换为<img src="https://storage.tutusouti.com/psst/files/dda8f7e5c7974212b3475578832656a5.jpeg?x-oss-process=image/sharpen,200"/>，则<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/4277a60bdf52460281b963a9c7deba22.png?x-oss-process=image/sharpen,200"/>可表示为（）。‌