我需要一张SIM卡。

When to use

This is the phrase to use when you want to purchase a SIM card for your mobile phone, typically at a phone carrier's store or a convenience store.

Grammar: Measure Word Usage

This sentence uses the structure: Subject + Verb + Number + Measure Word + Noun. '一张' (yì zhāng) is the correct measure word for flat, paper-like objects such as cards.

• 我 (wǒ): I
• 需要 (xū yào): need
• 一 张 (yì zhāng): one (measure word for flat objects)
• SIM卡 (sim kǎ): SIM card

Tone Sandhi for 一 (yī)

The number '一' (yī) changes to the fourth tone 'yì' when followed by a first, second, or third tone character. Since '张' (zhāng) is first tone, it is pronounced 'yì zhāng'.

Notes

A starter phrase for buying a SIM card at a phone store.