一般现在时：am/is/are+done The bridge is built every year.
现在进行时：am/is/are+being done The bridge is being built now.
现在完成时：have/has+been done The bridge has been built just.
一般过去时：was/were+done The bridge was built last year.
过去进行时：was/were+being done The bridge was being built in Oct.last year.
过去完成时：had+been done The bridge had been built by the end of last year.
过去将来时：would+be done He said the beidge would be built next year.
一般将来时：will+be done或am/is/are+going to be done The bridge will be built next yea