[Bug #1618083] Add missing word; make a few grammar fixes

Doc/lib/libsqlite3.tex

@@ -187,12 +187,12 @@ int, long, float, str (UTF-8 encoded), unicode or buffer.
 \end{funcdesc}
 
 \begin{funcdesc}{complete_statement}{sql}
-Returns \constant{True} if the string \var{sql} one or more complete SQL
-statements terminated by semicolons. It does not verify if the SQL is
-syntactically correct, only if there are no unclosed string literals and if the
+Returns \constant{True} if the string \var{sql} contains one or more complete SQL
+statements terminated by semicolons. It does not verify that the SQL is
+syntactically correct, only that there are no unclosed string literals and the
 statement is terminated by a semicolon.
 
-This can be used to build a shell for SQLite, like in the following example:
+This can be used to build a shell for SQLite, as in the following example:
 
     \verbatiminput{sqlite3/complete_statement.py}
 \end{funcdesc}