A:2.1×103J/(kg•℃)
B:4.2×103J/(kg•℃)
C:1.2×103J/(kg•℃)
D:条件不足,不能确定
(2015•玉林)如图示意某国国徽,读图完成问题.除国徽上的生物外,该国还有许多古老的物种繁衍至今,其主要原因有( )
China began to open to the outside world in the late 1970s. _________, there have been great changes in the country.
下列图示实验操作中,正确的是( )