Fill in the blanks with an appropriate verb form:

She threw a pen at me, but ……………………

missed

The appropriate verb form to fill in the blank is missed. The simple past tense of the verb "miss" is missed. The context of the sentence indicates that the pen was thrown in the past, so the simple past tense is the most appropriate tense to use.

The other options are incorrect.

• Had missed is the past perfect tense of the verb "miss".
• Have missed is the present perfect tense of the verb "miss".
• Missing is the present participle of the verb "miss".