运用植物组织培养技术，可以实现优良品种的快速繁殖，培育出大量不含病毒的幼苗，实现花卉的连续生产，请回答下列有关问题：

（1）进行组织培养时，常用____ 培养基，该培养基与微生物培养基的不同点在于成分更多为无机盐，在应用时常常添加____ 

（2）愈伤组织细胞的特点：排列疏松无规则，高度____ 化的呈____状态的薄壁细胞．

（3）培育被子植物花粉植株一般有两种途径：脱分化成____ 或愈伤组织，再经过诱导分化出____和根，进而发育成幼苗．

（4）确定花粉的发育时期，常用的染色方法有____法和____ 法．

下列实例属于超重现象的是（   ）

    An American skydiver has survived a 7, 600-meter jump from an airplane, although he did not use a parachute(降落伞). Luke Aikins dropped into a huge safety net on Saturday after falling for about two minutes over the desert in California. Aikins reached a speed of 193 kilometers per hour during the jump. He fell safe into a net. Cranes(起重机) ____ (hold) the net about 65 meters over the desert floor. The 42-year-old husband and father has jumped out of planes thousands of times, but never once  ____he left a plane without a parachute. Aikins said he was nervous before this jump. “We're talking about jumping without a parachute,” he told reporters. "I take that very  ____(serious). It's not a joke.” Aikins prepared for two years  ____(make) the jump. Three skydivers with parachutes made the jump with him. They recorded the event with a video and carried the  ____ (equip) that Aikins needed, like an oxygen mask. Aikins rolled in the air just moments before he hit the net so as to land on his back. The sky-diver did not move for several seconds as the net was lowered to the ground. Then, Aikins stood, waved his arms and hugged his wife.