小动物接触易挥发液态化合物的急性毒性试验，最适宜采用的染毒方法是
A．喂饲
B．灌胃
C．吞咽胶囊
D．静式吸入
E．皮肤敷贴
参考答案：D
波在传播过程中，若遇到障碍物或其他不连续的情况，而使波阵面发生畸变的现象称为波的衍射。
(71) analysis emphasizes the drawing of pictorial system models to document and validate both existing and/or proposed systems. Ultimately, the system models become the (72) for designing and constructing an improved system. (73) is such a technique. The emphasis in this technique is process-centered. Systems analysts draw a series of process models called (74) . (75) is another such technique that integrates data and process concerns into constructs called objects.
（72）是（）
A.image
B.picture
C.layout
D.blueprint
