He is struggling to understand the perfect tense in English.

He learned the past tense in Japanese.

This word has several variant forms.

When learning Japanese, it is important to remember words in dictionary form.

He wrote an ancient poem using the literary language form.

This textbook explains mainly in colloquial form.

He is completely nowhere to be seen.

Her necklace was in the beautiful shape of a butterfly.

This sentence is using the inclusive form.

This grammar rule is using the exclusive form.