What are common syntax errors in PHP scripts that lead to "unexpected T_STRING" errors?

Common syntax errors in PHP scripts that lead to "unexpected T_STRING" errors often occur when there is a missing or misplaced quotation mark in a string. This error indicates that PHP encountered a string where it was not expected, usually due to a syntax issue such as forgetting to close a string with a quotation mark. To resolve this error, carefully check your code for any missing or misplaced quotation marks in strings. Example PHP code snippet:

// Incorrect code with missing quotation mark
echo "Hello, world;
```

To fix the issue, add the missing quotation mark:
```php
// Corrected code with quotation mark added
echo "Hello, world";