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tokens: wavelengths, we can see that there appear simultaneous EUV flashes and enhanced 10830 Å absorption. Actually, the enhanced absorption at 21:31:00 UT has already appeared in Figure 4 . The EUV flashes over the sunspot certainly have a spatiotemporal association with the two valleys on the 10830 Å light curve, and at the same time, they are associated with the illumination of the two micro-flares. Though we need to carry out further detailed quantitative analysis with existing models, the nice correlation will serve as direct observational evidence supporting that the PRM mechanism really works. Here it is worth mentioning that Judge Pietarila ( 2004 ) reported no correlations between helium and He ii emission and overlying coronal emission. Their conclusions were made by analyzing quiet regions and coronal holes. Considering in the paper that the two micro-flares and the excitation site are over 5 Mm away, the excitation of helium atoms by EUV illumination should be a mean effect from overlying coronal emission as well as at least nearby coronal emission. Figure 6. Top and the third rows (panels S1–S8): snapshots for the micro-flare at ∼21:20:30 UT taken on the ground by NST and in space by AIA. AIA images are overlaid with contours of sunspots. The second and fourth rows (panels L1–L8): light curves for 10830 Å and EUV brightness from 21:00 UT to 21:40 UT obtained from the boxed areas shown in the upper corresponding images, with red curves from red boxes (over the sunspot) and blue curves from blue ones (over the sites of the two micro-flares). Two vertical dotted lines indicate the peak times of the two micro-flares. As mentioned in previous sections, the most notable phenomenon is that an oscillating absorption appears inside one flare ribbon when it sweeps into the sunspot. An overall description of this phenomenon is that a dark (absorption) strip rushes out into the sweeping forth sunspot ribbon and then returns back until the next several dark strips repeat the same behavior (Figure 1 , also please watch the online movie). From the space–time diagram, the oscillating behavior is revealed as a sawtooth-like pattern, the oscillating absorption strip actually starts when the ribbon reaches the inner penumbral region. For umbral flashes and even penumbral waves, the sawtooth behavior can be observed from spectrograms taken in certain chromospheric lines like Ca ii H K lines (Beckers Tallant 1969 ). It was also called a Z pattern with fast blueshift and slower redshift excursions, which were attributed to shock waves and post-shock falling back of the material contained in these shock waves. In this event, the observations were made in the He i 10830 Å blue wing −0.25 Å, which certainly highlights the blushift component. However, the 0.5 Å bandpass of the Lyot filter is comparable to the He i 10830 Å line width (∼0.75 Å) and the line is very weak, meaning slower redshift excursions will still be visible. So the features of blueshift and