It is OBLIGATORY to use a measure word when a numeral, a demonstrative pronoun, or an interrogative pronoun qualifies a noun.
1. Between a numeral and a noun.
numeral + measure word + noun
wǔ bēi chá 五杯茶 five cups of tea
sān běn shū 三本书 three books
yì diǎnr jiǔ 一点儿酒 a little bit of wine
liǎng wèi lǎoshī 两位老师 two teachers
Note that the numeral for 'two ' of something is 'liǎng两 ', not èr二.
2. Between a demonstrative pronoun (zhè这 this, nà那 that) and a noun, when the numeral is yī一 (one), yī一(one) has been omitted. Note that when used before numeral and measure words zhè这 and nà那 are often pronounced as zhèi这 and nèi那 in spoken Chinese.
zhèi这 or nèi那 + (one) + measure word + noun
zhèi běn shū 这本书 this book
nèi ge rén 那个人 that person
zhèi sān běn shū 这三本书 these three books
The numeral cannot be omitted if it is greater than one. Also note that
the demonstrative pronoun with a measure word is zhèi这 (this) or nèi那 (that), not zhèixiē这些 (these) or nèixiē那些 (those). In other words, in Chinese the singular demonstrative is used with numerals bigger than 'one ', i.e. 'this three... ' or 'that five... ' instead of 'these three... ' or 'those five... ' for multiple objects with
specified number.
See the examples below:
zhèi xiē shū 这些书 these books
When demonstratives are used to point at multiple objects with
unspecified number, Chinese uses zhèi xiē这些 (these) and nèi xiē那些 (those). When xiē些 , literally meaning 'a small amount ', is used, it serves as a
measure word and replaces the original measure word of the noun.
zhèi xiē běn shū. 这些本书 these books
It would be incorrect to use a measure word when you are already using
xiē些.
3. Between the interrogative pronoun nǎ/něi哪 (which) and a noun, when the numeral is one but has been omitted.
nǎ/něi哪 + (one) + measure word + noun
Něi běn shū? 哪本书? Which book?
4. Between the interrogative pronoun jǐ几 (how many; how much) and a noun. Jǐ几 is used for numbers smaller than ten. Jǐ几 also means 'several', 'a few' 'some' or 'a couple of ' and it requires a measure word before the noun. If the number is expected to be greater than ten, the interrogative pronoun should be duō shǎo多少 (how many; how much), which does not take a measure word.
jǐ几 + measure word + noun
Jǐ běn shū? 几本书? How many books? (expecting a number smaller than ten)
Compare withduō shǎo多少 for numbers greater than ten. It does not take a measure word.
Duō shǎo shū? (NO MEASURE WORD) 多少书? How many books? (expecting a number bigger than ten)