25． 这条运河历经数百年才修建而成，如今虽无昔日繁荣之景，但仍然是横跨东西的重 要水路。（as...as） Although this canal，which took hundreds of years to be constructed， is no longer as prosperous as it used to be，it is still an important waterway running from the east to the west.
参考答案
Although this canal，which took hundreds of years to be constructed，is no longer as prosperous as it used to be，it is still an important waterway running from the east to the west.