Itis（）formarinerstocombinetheSARTwithafloat-freesatelliteEPIRB.
A: essential
B: compulsory
C: optional
D: inadvisable
A: essential
B: compulsory
C: optional
D: inadvisable
C
举一反三
- Certain courses are compulsory while others are ( ). A: optional B: option C: curriculum D: obligatory
- College students have to take ____________ courses. A: Extracurricular B: Elective C: Compulsory D: Optional
- Business trips are mostly _____________. Meanwhile, the schedule is always full. A: optional B: compulsory C: empty D: friendly
- Inorderto(attain)ourobjective,itis(essential)thatwe(willmake)thebestuseofthelimitedresources(available). A: attain B: essential C: willmake D: available
- ForshipsequippedwithanSES,itis（）and（）fortheoperatortosendadistressalert. A: easy/reliable B: difficult/cheap C: stable/compulsory D: easy/expensive
内容
- 0
【单选题】In addition to compulsory courses, we have quite a few ________ courses at college. A: pursuit B: ecyclable C: optional D: moderate
- 1
You don’t have to write the essay if you don’t want to. It is __________. A: compulsory B: suitable C: optional D: alternative
- 2
They have done away with ______ Latin for university entrance at Harvard. A: influential B: B. indispensable C: C. compulsory D: D. essential
- 3
翻译成中文：A business letter should include all thenecessary information. It is essential to check the message carefully before itis sent out.
- 4
A．inaccessibleB．inadvisableC．inefficientD．incomplete A: inaccessible B: inadvisable C: inefficient D: incomplete