统一式燃烧室
参考答案：
由凹形的活塞顶面及气缸壁直接与气缸盖底面包围形成单一内腔的一种燃烧室。
放射性核素显像有别于单纯形态结构的显像，是一种独特的功能显像。
The relational database model requires the data be (71) through programs that don’t rely on the position of the data in the database. This is in direct (72) to the other database mode, where the program has to follow a series of pointers to the data it seeks. A program (73) a relational database simply asks for the data it seeks; the DBMS performs the necessary searches and (74) the information. The (75) on how the search is done are specific to the DBMS and vary from product to product.
（72）处填（）。
A．conduct
B．contract
C．contrast
D．construct
