sign up
Should Use "sign in"
As "sign in" if you are already a registered user,
or "sign up" to become a registered user.
check in
report报到
report to school到学校报到
registeration
Registration
开学的“报到”report for school
to tell somebody that you have arrived; for example for work or for a meeting with somebody or school
有没有听过 report for work?
同样的说法。
不 可 以 用
1) Check-in
Check-in is the process of announcing your arrival at a hotel, airport or sea port.
2) sign in
To record the arrival of another or oneself by signing a register.
3) registration (rj-strshn)
n.
1. The act of registering: voter registration.
2. The number of persons registered; enrollment.
3. An entry in a register.
4. A document certifying an act of registering.
4)sign up
To agree to be a participant or recipient by signing one's name; enlist: signed up for military service; signing up for a pottery course.
5)enrollment also enrolment (n-rlmnt)
n.
1. A record or an entry.
a. The act or process of enrolling.
b. The state of being enrolled.
2. The number enrolled:
The class has an enrollment of 27 students.
参考资料:Oxford Dictionary