‘jiù’ and ‘cái’: Here we will discuss these two adverbs as a pair, as suggested by Chu (1998), because the two adverbs manifest an intriguing feature in that they are both synonymous and antonymous. Both adverbs must be used in contexts that involve expectation (Chu, 1998: 95-101).
When ‘jiù’ and ‘cái’ are used with a ‘numeral + a classifier’, both adverbs express a small amount or quantity that is ‘less than expected’. In this case, they are interchangeable. Please look at the following examples:
Wǒmen jiù/cái xué le yībǎi duō ge Hànzì.
(We have only learned more than one hundred Chinese characters.)
Tā jiù/cái qù guo nàli yī, liǎng cì.
(He went there only one or two times.)
Zuò shōu yín yuan, yī ge xiǎoshí jiù/cái liù ge bàn Měiyuán.
(To work as a casher, the pay is only six and half dollars per hour.)
 Loar, J. K. (2011). Chinese syntactic grammar: functional and conceptual principles. New York: Peter Lang.