Weak market, after a sharp drop, look for a short-term rebound to retrace 0.382 or 0.50 of the day's decline, then you can take a short position on the rebound. Compared to Boll, it is basically the middle track of the 15-30 minute level. For example, tonight:

The resistance for BTC is at 100750-101312.

The resistance for ETH is at 2258-2290.

The resistance for SOL is at 131.85-133.5 (if it rebounds 7-9 points from the day's lowest point, taking a short position is relatively safe, slightly stronger rebound at 11 points).

If you can't catch it, just wait to buy the dip.