No one yet knows what made Derrick Bird attack these people, who seem to have included his twin brother and colleagues from work as well as total strangers, before killing himself.

目前还没有人知道什么让Derrick Bird在杀死自己前向这些人们发动袭击，其中似乎还包括他的孪生兄弟和同事以及完全不相干的陌生人。

youdao

And all those give as well a reference to offshore derrick design.

此方法也可供海洋井架电算参考。

youdao

Equipped with suitable derrick and well controlled device in drilling a shallow gas well water drills proved to be able to reduce shallow gas well drilling cost.

通过某浅层气井的施工实例，阐述了水井钻机安装合适的钻塔底座和并控装置，可降低浅层气井建井成本。

youdao

What they do is they sign a lease, and then a company comes along eventually and sets up a well and a derrick, and then they drill the well themselves.

NPR: Drilling for Gas in Dallas-Fort Worth

"All the injuries we had last year prepared us well for having to play without Derrick this year, " said the raspy voiced Thibodeau, who's favored to win the league's coach-of-the-year award for an unprecedented second straight season.

WSJ: Bulls: Does Chicago Need Derrick Rose?