I did not know what he was talking about. By now the second plane had struck Tower 2, but we did not hear anything.

我当时根本没弄明白他的意思。此时，第二架飞机已经撞上2号楼，但我们什么都没听见。

youdao

One 16-inch shell struck the control tower.

一发16英寸的炮弹击中了那座指挥塔。

《柯林斯英汉双解大词典》

North tower, 72nd floor (in office when plane struck)

当飞机撞击大厦时，位于北楼72层的办公室内

youdao

He included the airline in his claims for damages after American Airlines Flight 11 from Boston to Los Angeles struck the north tower of the trade center, killing 86 passengers and crew members, along with the hijackers.

WSJ: NY developer: Airline reneging on 9/11 promise

In 2009, 16 tourists were injured when their balloon struck a cellphone transmission tower.

NPR: Fiery Balloon Accident Kills 19 Tourists In Egypt

As usual, the event's proceedings will pause six times to commemorate the moments each tower was struck and fell and the moments the Pentagon was struck and United Airlines Flight 93 crashed to the ground in Pennsylvania.

WSJ: Politicians Silenced at 9/11 Event