Write the IUPAC name of `PH-CH=CH-CHO`.

Explanation

To write the IUPAC name of the compound `PH-CH=CH-CHO`, we can follow these steps:

### Step 1: Identify the functional groups
The compound contains two functional groups: an aldehyde (CHO) and a phenyl group (PH). The aldehyde group has a higher priority in naming.

### Step 2: Number the carbon chain
We will number the carbon chain starting from the end closest to the aldehyde group to give it the lowest possible number. In this case, we start from the carbon of the aldehyde:
- Carbon 1: CHO (aldehyde)
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