afternoon – sha-wu
Written as xiàwŭ or xiawu
To remember that afternoon is pronounced sha-wu (xiawu) in Mandarin Chinese, use the following mnemonic:
In the afternoon I like to take my shark for a walk in the woods (sha-wu).

Tones
1. Sha (shark) is a 4th tone with \ as an accent.
Associate being warm, a 4th tone, with lowering things like trip or slide down. See Tones and Mnemonics.

The shark slid down the slide.
2. Wu (woods) is a 1st tone with — as an accent.
Associate being warm, a 1st, with lowering things like trip or slide down. See Tones and Mnemonics.

The woods were shaped like a horseshoe.
Remember
Sha = 4th tone = \
Wu = 1st Tone = —