Give the IUPAC names of the following compounds:
` CH_2 =CH - overset(CH_2CH_3) overset(|)(CH ) - underset(Cl) underset(| ) C=CH_2`

Explanation

To determine the IUPAC name of the given compound, we will follow these steps:

### Step 1: Identify the longest carbon chain
- Count the number of carbon atoms in the longest continuous chain that includes the double bonds. In this case, the longest chain has 5 carbon atoms.

### Step 2: Number the carbon chain
- Number the carbon atoms in such a way that the double bonds and substituents (like Cl and ethyl groups) get the lowest possible numbers.
- Start numbering from the end closest to the first double bond. This gives us the following numbering:
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