This way, the sentences will run together without starting a new row for each sentence:
<input type=checkbox name=sentence1 value=1>This is a sentence. <input type=checkbox name=sentence1 value=2>This is a sentence. <input type=checkbox name=sentence1 value=3>This is a sentence. <input type=checkbox name=sentence1 value=4>This is a sentence.
or with a table, each sentence gets its own row:
<table>
<tr>
<td><input type=checkbox name=sentence1 value=1></td>
<td>This is a sentence. </td>
</tr>
<tr>
<td><input type=checkbox name=sentence2 value=1></td>
<td>This is a sentence. </td>
</tr>
<tr>
<td><input type=checkbox name=sentence3 value=1></td>
<td>This is a sentence. </td>
</tr>
<tr>
<td><input type=checkbox name=sentence4 value=1></td>
<td>This is a sentence. </td>
</tr>
</table>