Question

Find the sentence in each one that breaks the unity of the paragraph.

Answer 1

During the later stages of World War II, pilots of advanced fighter aircraft experienced strange and alarming behavior on the part of their machines when in a high-speed dive they approached the speed of sound. Their planes buffeted and wrenched about. Controls sometimes reversed or became ineffective, and increased drag set in. The Concorde regularly flies at several times the speed of sound. In some cases the wings tore off, and the plane broke apart and crashed. Because of these experiences there developed the idea of a sonic wall, a "sound barrier" of some kind through which no aircraft could pass unscathed.