This is from Macmillan English Grammar in Context by Michael Vince.
Alan Chester is a 25-year-old journalism student from Ohio who is taking six years to complete his undergraduate degree. In order to pay tuition fees and other expenses he is working four days a week in the university kitchen, while in the university holidays he does part-time job.
According to the book my answer "is working" is wrong.
I find it hard at the moment to study and pay my bills at the same time.
My choice "I find" is wrong.
Some students spend time experimenting with difficult courses before choosing their major.
I used "spend" it is wrong.
Could you please explain to me what makes my choices wrong?