The intake valve closes at _____ for a low-speed engine and at _____ for high-speed four-stroke petrol engines.
1
60 deg after BDC; 10 deg after BDC
2
10 deg before BDC; 60 deg before BDC
3
60 deg before BDC; 10 deg before BDC
4
10 deg after BDC; 60 deg after BDC