推理(a)“SIP→SOP”与推理(b)“PIS→SIP”的有效情况是( )
A. 都有效
B. 都无效
C. (a)无效
D. (b)有效
E. (b)无效
根据命题变形的直接推理,下列推理形式有效的是( )
A. SOP→POS
B. SAP→SIP
C. SEP→SOP
D. PIS→SIP
E. SAP→PIS
Please match the following aspects American people use to compliment with the suitable examples.
Please match the following words or phrases with the best Chinese meaning.