Was his average speed incorrectly declared to be 299 miles per hour or 289 miles per hour?

题目

Was his average speed incorrectly declared to be 299 miles per hour or 289 miles per hour?
请解释一下declared to be,我不懂这个to be是怎么回事,是本来就declare to do 还是什么词组,如果直接declared 299 miles可以吗,把to be 去了,可为什么要加to be,请详解

答案

1 declare a to be b 宣布A成为B.declared to be- - - 被动语态----被宣布成为 -- -
declare(谓语) A（宾语） to be B （宾语补足语）
be declared(谓语) to be- - - （主语补足英）