—This is the law of nature.
A:for a few minutes
B:for all the time
C:for some years
下列常见的水生生物中属于软体动物的是( )
读图,图中①—⑥分别代表岩浆、沉积物、喷出岩、侵入岩、沉积岩、变质岩,试判断图中代表沉积岩、变质岩分别是( )
体循环和肺循环是两个独立的过程.(判断对错)