[求助]请教大全142

以下是引用dreadpower在2003-12-22 21:24:00的发言：
142.As U.S. nuclear attack submarines prowl their familiar haunts deep within the oceans of the world these days, they increasingly are engaged in missions far different from the tasks for which they were built and for which their crews were trained over the last forty years.
(A) they increasingly are engaged in missions far different from the tasks for which they were built
(B) the missions they increasingly engage in are far different than the tasks they were built for
(C) they engage increasingly in missions that differ significantly from the tasks they were built for
(D) the missions they engage in are increasingly different than the tasks for which they were built
(E) they increasingly engage in missions far different than the tasks for which they were built
     答案是A。有几个问题要请教

     1。A选项中的be engaged in和其他选项中的engage in有什么区别？？？

个人认为，两者使用都可以， 意思上一个表示主动， 一个表示被用于，只不过原句的合理意思应该保留。

     2。increasingly副词，A选项中increasingly修饰engaged，但是我感觉increasingly位置不对，应该是they are increasingly engaged in。。。能解释一下吗？？
通常的副词作状语的 位置只要不是 插入在 谓语与宾语之间，都没有太大的错误。

          还有they engage increasingly in （单看这个表达）对吗？？
这个表达没有问题。