The idea of causality, in the sense of causing a person to do a
thing, is expressed in Chinese by the use of the auxiliary verbs
\{kau}/ (敎) and \{tsha}/ (差). Thus “I caused him to do it,” would be
\{°ngoo kao yi tsoo°}/ (我敎伊做). “I caused him to go,” would be \{°ngoo
tsha yi chi}/ (我差伊去). The word \{tsha}/ literally means “to send.”
The word \{kau}/ is the same as \{kyau°}/, but used with different
pronunciation and different tone. When one of higher rank causes a
person of lower rank to do a thing the word \{s°}/ (使) is used. Thus
\{S° °ngoo ieu-mung}/, “Caused me to sorrow.”
“Must” is expressed by the expressions \{tsoong-iau°}/ (總要),
\{pih-ding° iau°}/ (必定要), \{ih-ding° iau°}/ (一定要).
“It must be” is \{tsoong °z}/ (總是). Thus “It must be so” is
\{tsoong-°z zeh-ke°}/ (總是實蓋).
“Ought” implying obligation, is expressed by \{iung-ke}/ (應該). Thus
“You ought to do it” is \{noong° iung-ke tsoo° kuh}/ (儂應該做個).