She can

"Any questions?" The teacher walks down to the centre of the hall and surveys the students. Christa feels like the teacher's eyes linger a little longer on her than anyone else, and the nerves begin. She looks at the front cover of her exam paper, AQA CHY1H, and the words seem to blur. Looking up, she sees her teacher answering some of the other childrens questions, and tries taking a deep breath to calm herself down.
"OK, you have 25 minutes to complete this exam." The teacher's voice booms over the hall. "And this starts just as soon as the adjudicator gets here, she's late."
   
The panic sets in, and Christa looks down at her paper once more. As she picks up the pen to write her name, her hand shakes, and she has to put it down again. She hears the teachers footsteps echoing as she walks down the hall, and hopes she is going to greet the adjudicator, and just get the exam started. Instead, she feels the teacher bending over her, her face so close to Christa's she can feel her breath, "Christa? Are you OK love?"
   
Christa nods, willing her to go away. The teachers intentions are good, but it seems like she's prolonging the absolute agony of the wait. "OK..." her teacher replies doubtfully, "Just take deep breaths OK honey, you have revised for this, you are going to be just fine."
She walks away, and Christa breathes a sigh of relief. Focusing now on the clock she watches the seconds tick by, imagining each second is an hour, her entire life wasting away in this room.
The teacher takes control. "OK, the adjudicator clearly isn't going to be here soon, so I'm going to start the exam. Exam conditions people, NO communicating, if you finish before the end, check through, and then put your head on your arms and have a sleep!" She talks confidently, "Oh, and kids, You CAN because you think you CAN, school motto remember? And I know you can too." She smiles round at them. "OK, start now."
        "I can because I know I can..." Christa repeats to herself, and she starts writing.
25 minutes later she's free, it's over. Her teacher comes up to her, "How did it go, I was worried about you back there. Christa smiles at her teacher. "OK miss, once you shut up!" And runs off laughing