The only word that can be used before “chalk" is 

Questões de assuntos semelhantes

• A wrongly pluralised English uncountable noun can be found in alternative:
• Na frase, “Here are three leaves”, a palavra destacada constitui o plural de um substantivo parte de um grupo, no qual o plural é feito...
• The underlined word in “Since the empirical corpus work started” (3rd paragraph) is a
• The words running (line 2), entering (line 4), outgoing (line 5), operating (line 7) are respectively:
• Marque (V) para verdadeiro e (F) para falso de acordo com o plural dos substantivos. ( ) Similar kinds of analyses can diagnose two other forms...