A:胃
B:大肠
C:小肠
D:口腔
It is u____ acknowledged that people cannot succeed or achieve their targets without a strong will and persistence.
如图所示,滑动变阻器有ABCD四个接线柱,将其中的两个接线柱接入电路,改变电路中电流的大小,正确的连接方式最多有( )