[填空题]I first met Lisa three years ago. She (work) ______ at a radio shop at the time.

[单项选择]Martha says the first three years of the business were
A. not very successful.
B. surprisingly good.
C. very interestin

[填空题]I first met Grace five years ago. She ______ (work) at a radio studio at that time.

[单项选择]Three years after its first test flight ended in an explosion, NASA on March 27 successfully launched an experimental jet that the agency believes it (47)______ a record-setting speed of about 5,000 mph. The unpiloted X43A made an 11 second rocket boosted flight, then went through some twists and (48)______ during a six-minute glide before (49)______ into the Pacific Ocean about 400 miles off the California (50)______ . Flight engineer Lawrence Huebner said preliminary data (51)______ the needle-nosed jet reached a maximum speed of slightly over seven times the speed of sound, or about 5,000 mph, after a rocket boosted it to about 3,500 mph. Huebner said it was the first time an "air breathing" jet had ever traveled so fast. The rocket powered X15 reached Mach 6.7 in 1967. NASA built the X43A under a $250 million program to develop and test an (52)______ type of engine called a supersonic combustion ramjet, or scramjet. In theory, the air breathing engine could (53)_____